# Posts by MathMate

Total # Posts: 11,744

**science**

suggested approach: create a class for each Employee, with class properties as integer code string name double salary char category double bonus double totalSalary with class methods called double calculateBonus() void printEmployee() Use switch-case to calculate bonus. Add ...

*January 1, 2017*

**physics**

The most important part of answers of this type of physics problems is the assumptions made to arrive at the answer. With a given answer, these assumptions are usually given, but not in the present case. The given answer corresponds to the following assumptions: 1. D>>H ...

*January 1, 2017*

**ChemistryStociometry**

1. Calculate moles of CoCO3 =6.0/(58.933+12.0+3*16.0) =6.0/118.9 =0.0504 mol 2. Calculate moles of HCl =40/1000*2.0 mol =0.080 Using stoiciometric ratios CoCO3 used = 0.08*1/2=0.04 mols => CoCO3 is in excess (<0.0504). The remaining answer can be obtained by finding the ...

*January 1, 2017*

**Math**

Principal and interest after 8 months =8000(1+0.0276/12*10)=8184 Let a=initial repayment amount (n=1), then the repayment amount at month n a(n)=a*r^(n-1) where r=2 Total repayment amount Sum=a(1)+a(2)+...+a(10) =a(r^10-1)/(r-1) =1023a Equate total amount owing with amount ...

*January 1, 2017*

**math**

Do you mean volume=54 dm³ ? Use 1 dm³=1000 cm³ volume=length*width*height and solve for height.

*January 1, 2017*

**chemistry AS**

Analyse the name piece by piece. Pentene = a 5-carbon hydrocarbon with a single double bond. Pent-2-ene has a double bond in the second carbon atom. (Z) at the beginning means that the two CH3 groups are on the same side of the double bond (Zusammen) means "together"...

*December 31, 2016*

**Math**

The rebound height is a geometric sequence, i.e. H(n)=H0*r^n where n=number of bounces. For H0=16', r=0.25 H(1)=16*(0.25)^1=4' H(2)=16*(0.25)²=1' ...

*December 30, 2016*

**Fun Physics**

Yes, I did it differently, and this time I can eliminate all other variables. I get 0.06 m/s only if the final speed has been reduced by 0.59 of the original speed. If the final speed is 0.59 of the original speed, then μ=0.1396. Let: t=theta=16.1° g=acceleration due to...

*December 30, 2016*

**Fun Physics (to Rose)**

It's an interesting problem. Do you happen to be given the initial velocity as 0.7 m/s ? I have an impression that μ is dependent on the initial velocity.

*December 30, 2016*

**maths**

Propagation value of variable is a very useful iterative method for solving system of equations, especially if certain variables have constraints. The given example is especially favourable example for the method because the coefficients are diagonal dominant. We rewrite the ...

*December 30, 2016*

**discrete mathematics (to yopo)**

Thank you! I appreciate your comments. Feedbacks are appreciated, good or bad!

*December 30, 2016*

**discrete mathematics**

Number of arrangements of n persons in n positions is n!. Example, 3 people, 3 places, there are 3!=6 possible arrangements. a) If Syahirah mush be in the third position, there are 5 people left for 5 places. Use the formula above. b)If Dinesh must be second, and Felina third...

*December 30, 2016*

**Statistics**

How many are in the family?

*December 29, 2016*

**algebra (to Rehan)**

Please check your own posts and "related questions" before reposting. This is the sixth post of the same question in the last 50 hours, answered by 5 different tutors.

*December 29, 2016*

**math**

This question has been answered 4 times in the last 50 hours. The links are the first four under "Related Questions" below. It is always to your advantage to go through the "Related Questions" before you even press the "Post Answer" button. Also, ...

*December 29, 2016*

**maths**

a shorter way. 1/sin(x)+1/cos(x)=2√2 multiply by sin(x) on both sides, 1+tan(x)=2√2 sin(x) square both sides (1+tan(x))²=8sin²(x)=8tan²(x)/sec²(x) using 1+tan²(x)=sec²(x), (1+tan²(x))(1+tan(x))=8tan²(x) set t=tan(x), and ...

*December 29, 2016*

**maths (to Steve)**

Nice thought! Thank you!

*December 29, 2016*

**maths**

Perhaps there is an easier way to solve this problem, but this is all I have for now. Where there is no confusion, sinX=sin(x), cosX=cos(x) We'll work on the left side first cscX+secX =1/sinX+1/cosX =(cosX+sinX)/(sinX*cosX) =2(cosX+sinX)/sin(2x) [use sin(2x)=2sin(x)cos(x...

*December 29, 2016*

**MATHS**

Clock runs 10 minutes fast every 24 (real) hours. So clock shows 24*60+10=1450 minutes after 1440 minutes. 3PM-10PM=2+15 hours = 17 hours = 1020 minutes. Actual time passed from 10PM = 10pm + 1020*(144/145) =10 pm + 1012 28/29 minutes =14:52:57.93

*December 28, 2016*

**Computer Science**

If you know the ascii code, 48-57 0-9 65-90 A-Z 97-122 a-z Most of the remainder (0-127) are special characters, except space (32) and perhaps other white space characters. It will consist of one while loop to check each of the above. For the extended ascii table, see http://...

*December 28, 2016*

**Math(A.P)**

You're welcome!

*December 28, 2016*

**Math(A.P)**

Start salary=700 Top of scale = 1500 Number of increments to reach top = (1500-700)/40=800/40=20 Assume increment is annual, so it takes 20 years to reach the top of the scale.

*December 28, 2016*

**maths**

If it is open at both ends, then the lengths are the same. Volume of steel is obtained by subtracting the inner area from the outer area and multiplied by the length. V=(π/4)(24²-20²)(55) cm³ = 2420π

*December 28, 2016*

**Math**

annual interest = 4*22.05=88.20 $1960 earns 88.20 interest in one year, so annual interest, i=88.05/1960=0.045, or 4.5% per annum

*December 28, 2016*

**math**

total loan=$20092 Down=$2000 Amount to finance, A=20092-2000=$18092 term = 5 years compounded monthly monthly interest, i= $0.069/12=0.00575 R=1+i=1.00575 number of periods, n = 5*12=60 Monthly payment, P=AR^n*(R-1)/(R^n-1) = 18092*(1.00575^60)*(0.00575)/(1.00575^60-1) =357.39...

*December 27, 2016*

**Chemistry**

For the diluted acid, C1,V1=diluted acid C2,V2=sodium hydroxide NaOH+HCl=NaCl+H2O Use CiV1=C2V2 C1*25.0 mL=0.5M * 15.00 mL C1=0.5M*15.00/25.0= 0.3 M Concentration of original hydrochloric acid = 0.3 M * (250.0/25.0) = 3 M (note only one significant figure is retained as a ...

*December 26, 2016*

**HELP PLEASE**

The translation rule is T(Δx,Δ)(x,y)->(x+Δx, y+Δy) .......... (1) Now we need to find Δx and Δy. We know that 7+Δx=2 -3+Δy=5 Solve for Δx and Δy and substitute in the transformation rule (1)

*December 23, 2016*

**trigonometry**

use sec²A=1+tan²A and let t=tan(A) sec(A)-tan(A)=10 √(1+t^2)-t=10 √(1+t^2)=(t+10)² 1=20t+100 t=-99/20 A=atan(-99/20)=-78.5788 (approx.) sec(A)=1/√(1+t^2)=101/20 cos(A)=1/sec(A)=20/101 sin(A)=-sqrt(1-(20/101)^2)=99/101 (note: A is in Q4, so sin(...

*December 23, 2016*

**Probability & Statistics**

Calculate Z as follows: z=(x-μ)/σ =(11000-8000)/1000 =3 From probability tables, find P(Z>z). P(Z>3)=1-P(Z<3)=1-0.99865=0.00135

*December 23, 2016*

**maths**

Use the point of division formula. Let the divided segment be PABCQ Then r1=PA/PQ=1/4 r2=PB/PQ=2/4 r3=PC/PQ=3/4 Applying the point of division formula to points A, B and C: A(a+r1(c-a), b+r2(d-b)) B(a+r2(c-a), b+r2(d-b)) C(a+r3(c-a), b+r3(d-b)) For more explanations and ...

*December 23, 2016*

**math**

"Will paid 1/3 of the dinner bill." means Micah and Sue paid (1-1/3)=2/3 of the bill. If Micah and Sue paid in the ratio 2:5, that means Sue paid 5/(2+5)=5/7 of their portion. $6÷5/7=$8.40 which is 2/3 of the cost of dinner. Proceeding the same way, 8.40&...

*December 23, 2016*

**algebra (To adiba)**

The question is not clear when out of context. Are you working with arithmetic or geometric progression? "rate of growth" could be an amount (arithmetic) or a ratio (geometric). Your answer is (almost) correct for linear growth (arithmetic). You only have to put the ...

*December 23, 2016*

**Maths**

We have AD perpendicular to BC. So triangle ABD is right-angled at D. AB=7, BD=3, therefore by Pythagoras theorem, AD=√(AB²-BD²) =√(7²-3²) =√40 Construct triangle ABD with the given dimensions. Extend BD to C such that BC=13. Join A and C ...

*December 23, 2016*

**Transformations (to Keith)**

Keith, please refrain from using different screen names. Also, please mention that you are reposting the question, and reposting within a short time could mean duplicate efforts by tutors, and hence slow the answering process. Your previous question has also been answered here...

*December 23, 2016*

**Compound interest (info please)**

Sorry, more details required. The following details seem to be subject to interpretation. Please give your comments. 1. the advance payment in December is a prepayment for the next two months. Does that practice continue for the rest of the loan repayment? 2. Is the 13th month...

*December 23, 2016*

**Compound interest (info please)**

Is the interest rate given? When was the 13th month advance payment paid, Dec.15 or January 15?

*December 23, 2016*

**Transformations - Maths**

The general transformation equation is: g(x)=a*f(b(x-h))+k where h=horizontal translation (right if h>0) b=horizontal scaling (stretch if 1/b>1) a=vertical scaling (stretch if a>1) k= vertical translation (up if k>0) applied in the above order, i.e. according to ...

*December 22, 2016*

**Probability**

similar to the APGAR test for newborns. Give it a try and post what you get.

*December 22, 2016*

**Probability**

Interesting problem. Check if binomial theorem applies. 1. Is each trial a Bernoulli trial (either success or failure)? Yes 2. Is probability of success (Apgar><6) known and remain constant throughout experiment (audit)? Yes 3. Are trials (result of each birth) ...

*December 22, 2016*

**Geometry**

hint: http://study.com/academy/lesson/reflexive-property-of-congruence-definition-examples.html

*December 22, 2016*

**data management gr.12**

You're welcome!

*December 22, 2016*

**data management gr.12 (to Jenna)**

A tree diagram includes the related probabilities, which is the real purpose of the tree diagram, because it then enables us to get the probability of each situation. /positive(0.98*0.02=0.0196) &...

*December 22, 2016*

**algebra 2**

For the point (x0,y0), error=y0-f(x0) SSE=Σerror² =Σ (y0-f(x0)² point error error² (3,6) 2 4 (6,2) -4 16 (9,10) 2 4 --------------- total = (4+16+4)=24

*December 22, 2016*

**math**

"What is 3 times the quotient of n divided by 5?" "...the quotient of n divided by 5"=n/5 "...3 times..." = 3* So put it all together: "3 times the quotient of n divided by 5" =3*(n/5)=3n/5

*December 22, 2016*

**data management gr.12**

This is a typical case of application of the binomial distribution, which requires: 1. probability of success (0.3) is known and remains constant throughout the experiment. 2. each trial is independent of the others. 3. there are exactly two possible outcomes, success or ...

*December 22, 2016*

**data management gr.12**

Contrary to probability calculations, we do not need to divide by XC9 when finding the number of arrangements. C(2,1)*C(3,1) is correct for the first two items. For the toppings, since we are allowed 0 to 4 toppings, the number of choice available equals the power set, or 2^4...

*December 22, 2016*

**data management gr.12**

ok, that sounds reasonable. If you like, you can continue with your method, which is (7C3*9C5)+(7C4*9C4)+(7C5*9C3)+(7C6*9C2)+(7C7*9C1) or, equivalently, 16C8-(7C0*9C8+7C1*9C7+7C2*9C6) which gives (or should give) the same result above. In doing counting problems, it is always ...

*December 22, 2016*

**data management gr.12**

I would like to see, in your interpretation, what each of the expressions mean. (7C3 x 4C2) (7C4 x 4C1) (7C5 x9C0)

*December 22, 2016*

**data management gr.12**

It would depend on the denominations. If the denominations are coprime with each other, then the number of different sums would equal to the power set of the coins. If |A|=3, |Power set (A)|=2^3. That includes the amount $0, i.e. no coin used. A notable example would be for ...

*December 22, 2016*

**Chemistry**

Here it is: H2SO4: 500 g 35% w/w H2SO4 contains 500*0.37 g pure H2SO4, or 500*0.37/0.96 g of 96% (w/w) H2SO4 =192.71 g of 96% H2SO4 =192.71/1.840 mL of 96% H2SO4 =104.73 mL. of 96% H2SO4 H2O: Volume of diluting water = 500-192.71 g =307.29 g = 307.29 mL. Summary: use 104.73 mL...

*December 22, 2016*

**Chemistry**

If you do not have the means to weigh the chemical, and if an approximate concentration is needed, than use the approximate value of density=1.840 g/mL to estimate the weight from given volumes. If you need a modified version without weighing, please let us know. It is ironic ...

*December 22, 2016*

**math**

If you want just numerical value, then a+b=atan(2/3)=33.69° a-b=atan(2/5)=21.80° 2b=atan(2/3)-atan(2/5) tan(2b)=tan(atan(2/3)-atan(2/5)) =0.210526

*December 22, 2016*

**Maths**

75cm

*December 22, 2016*

**Maths**

In a rectangle, the perimeter is given by perimeter=2(length+breadth) 250=2(length+50) Solve the above equation for length.

*December 22, 2016*

**Math**

Hint: The three sides cannot even form a triangle, because 20>5+10. Let X=length of fourth side, then Since 20-(5+10)=5, the fourth side must be greater than 5, or X>5 Similarly, the fourth side cannot be longer than the sum of the other three sides, otherwise the ...

*December 22, 2016*

**Maths**

Let N="a number" "When 100 is added to a number the result is 50 more than 3 times the number" translates to 100+N=50+3N Solve for N.

*December 22, 2016*

**data management gr.12**

Expected value, E[x]=Σpixi Now complete the table below sum P(sum) X(sum) 1 1/6 $10 2 1/6 $9 3 1/6 $8 4 1/6 $7 5 1/6 $6 6 1/6 $5 E[X]=ΣP(sum)X(sum) =(10+9+8+7+6+5)/6 =45/6 =7.5 Cost to play the game = 7.0 Expected winning = 7.5-7.0=0.50 I leave it to you to find ...

*December 21, 2016*

**data management gr.12**

The available options would therefore be to say that P(Z)=1 for Z>2.9, and P(Z)=0 for Z<-2.9.

*December 21, 2016*

**data management gr.12**

n=270 (>40) p=0.2 q=1-0.2=0.8 np=270*0.2=54 (>10) nq=270*0.8=216 (>10) All prequisites for normal approximation are satisfied. μ=np=54 s=std dev=√(npq)=sqrt(43.2) a) P(X≥100) apply continuity adjustment Z=(99.5-μ)/s=6.92 P(Z≥6.92)~1-2.26*10^(-12) =1 ...

*December 21, 2016*

**data management gr.12**

In a large population, a sample of 40 will not appreciably affect the probability of the population, hence the binomial distribution is applicable, namely P(x)=C(n,x)p^x*(1-p)^(n-x) p=0.35, n=40 a) E(x)=np b) P(0)=C(n,x)p^(x)*(1-p)^(n-x) =C(40,0)(0.35^0)(0.65^40) c)P(x>=3...

*December 21, 2016*

**math**

You're welcome!

*December 21, 2016*

**math**

You get the idea, but there is something missing. You have A(0)=125 A(1)=118.01 A(2)=111.02 ... A(n)=125-6.99n So when the card is used up, A(n)=0, or 125-6.99n=0 Solve for n=125/6.99=17.88 Drop the fraction to get 17 as the maximum number of apps he can download.

*December 21, 2016*

**MATH**

1. get familiar with finding the equation of the line using the Point-Slope form: (y-y0)=m(x-x0) m=-4/3 (x0,y0)=(12,6) Line L : (y-6)=-4/3(x-12) Simplify y=-4x/3 + 16+6 or y=-4x/3+22 To find other points on the line, substitute 3 different values of x and evaluate the ...

*December 21, 2016*

**Math**

See response at: http://www.jiskha.com/display.cgi?id=1482369962

*December 21, 2016*

**math**

See response at: http://www.jiskha.com/display.cgi?id=1482373766 Preferably do not change your screen name, and for repost, you could mention the link to the previous post that was not answered so there will not be duplicate efforts by different tutors. Thank you for your ...

*December 21, 2016*

**Math**

remaining area = 80*50-4*(5*5) =400-100 = 300 sq cm Mass = density*volume Density of metal = 2.5 g/cm³ Volume=300 sq cm *2mm =300*0.2 cm³ =60 cm³ So mass of open box?

*December 21, 2016*

**math**

Here's the table of P(Z') for Z=3.0 to 7.9 in steps of 0.1 3 1.3498E-3 9.676E-4 6.8713E-4 4.8342E-4 3.3692E-4 2.3262E-4 1.591E-4 1.0779E-4 7.2348E-5 4.8096E-5 4 3.1671E-5 2.0657E-5 1.3345E-5 8.5399E-6 5.4125E-6 3.3976E-6 2.1124E-6 1.3008E-6 7.9332E-7 4.7918E-7 5 2....

*December 21, 2016*

**math**

Quite true. If you do not have access to software nor calculator, this might be a problem using paper tables. You can try the following: 1. following link gives probabilities for z=0,1,2...50 but does not give fractional z values. 2. if possible, find a calculator that gives ...

*December 21, 2016*

**math**

The proper way to calculate P(x≥90) is to sum the binomial probabilities from 90 to 270. Using the computer, it should not be a problem. Using a calculator will need a little patience. For P(x≥90), np>10, npq>10 and with a sample of 270 people (n>>40), you ...

*December 21, 2016*

**Chemistry**

You need w/w solution, so we assume 1. 96% is w/w to start, 2. density of water = 1 g/mL 3. volume of mixture equals sum of volumes (=> approximation). We know that 500 mL of 37% w/w H2SO4 contains 500*0.37=185 g by weight of pure H2SO4. Concentrated H2SO4 has a density of ...

*December 21, 2016*

**math**

Kamil Soliciting an answer from a forum and using it as your answer is considered cheating by most educational institutions. Do you realize that teachers of your school check various forums for students who cheat? Here's an example to a similar question: 20% of 35 apples ...

*December 21, 2016*

**math**

You're welcome!

*December 21, 2016*

**math**

Yes, your answer is correct. To check, compare 75/200=0.375 500/1333.333=0.375 However, biologists use a more elaborate method to calculate. The proportional method used above assumes replacement of the sample after each recapture, which is not (usually) the case. When the ...

*December 21, 2016*

**Math**

The sum of the other two angles is 180-110=70 °. The sum of half of the other two angles is 70/2=35°. Therefore the angle between the bisectors of the other two angles = 180-35 = 145°.

*December 21, 2016*

**Structural Steelwork**

Take a piece of paper, and sketch the geometry as describe below to make a sketch that you can follow the steps. 1. Sit the triangle on the x-axis, with the left vertex A at origin, so that (0,900) is the other vertex B. The third vertex C has coordinates (450, 450√3) 2...

*December 21, 2016*

**data management gr.12**

Actually, the probability table should include the case P(0) as well. Do you know how to make a tree diagram? This is a foolproof way to make a distribution table, as long as it is not too complicated. In this case, you will have 2^4=16 "leaves", i.e. where the ...

*December 20, 2016*

**data management gr.12**

For (a), you may have double counted some cases, since the total is 1381/1050 >1, whichis impossible.

*December 20, 2016*

**math**

It's almost the same as the silt/soil problem. Let x be the volume of metal in oz needed, then (0.9x+3)/(x+3)=0.92 Solve for x. Do not forget to distribute when you cross multiply.

*December 20, 2016*

**math**

4 cubic ft (cf) of soil contains 4*10%=0.4 cf of silt If we add x cf of silt, total volume = 4+x volume of silt = 0.4+x Given the new percentage is 60%, we have (0.4+x)/(4+x)=0.6 Solve for x by cross multiplication: 0.4+x = 0.6(4+x)=2.4+0.6x transpose and solve for x x-0.6x=2....

*December 20, 2016*

**math**

Let h=height of the box. Then width=120/h length=168/h We know the area of the base is Ab=316 so Ab=width*length, or 316=(120/h)*(168/h)=(120*168)/h². Solve for h h=√(316/(120*168) =12√35/√79. Use the above equations above to find length and width.

*December 20, 2016*

**algebra**

Method 1: Use calculator, and do not forget to surround the numerator and denominator by parentheses, i.e. type in: (9.6*10^2)/(3.2*10^5) Method 2: (easier way) (9.6*10^2) ------------ (3.2*10^5) Note that 9.6/3.2=3, and 10^2/10^5=10^(2-5) =10^(-3) so the answer is 3.0*10^(-3...

*December 20, 2016*

**Alebra**

Example similar to the first one: solve 7x-9>61 Add 9 to both sides 7x-9+9 > 61 + 9 7x > 70 Divide by 7 (on both sides) 7x/7 > 70/7 x > 10 [answer]

*December 19, 2016*

**HELP ME PLZ MATH**

Great!

*December 19, 2016*

**HELP ME PLZ MATH (to savepuppy)**

When we go to the supermarket, with four similar items at different prices and packaging, we need to find the unit price of EACH of the four items in order to determine the best (lowest) unit price. Unit price can be found by the formula unit price = price / number of units or...

*December 19, 2016*

**Math**

1. find Z-score = (X-mean)/stdev =(67-65.5)/(2.5) =(1.5)/2.5 =0.6 2. Look up standard normal distribution tables for one-tail where Z-score = 0.6 P(x<X=67)=0.7257469 [from tables for Z=0.6] For part b, find similarly P(x<X=64) then P(64<x<67) =P(x<67)-P(x<64)

*December 19, 2016*

**math**

ME=Z√(0.25/n) For 90% confidence level, and ME=1% Z=1.644854 [ from tables for two tale at 95%] => 0.01=1.644854√(0.25/n) => n=(1.644854/0.01)^2*0.5 =6763.86 ~ 6764 persons

*December 19, 2016*

**Algebra**

M' means the complement of M. M' will encompass all the elements in the universal set but NOT in the set M. So please give it another try.

*December 19, 2016*

**Math (1 Question)**

The answer is here: http://www.coolmath.com/prealgebra/06-properties/08-properties-multiplicative-identity-01

*December 19, 2016*

**Algebra 9th**

In problems of this type, it is easier if you could make a scatter plot (or dot-plot) of the data before starting the calculations. In case you spot an outlier, you will have to occasion of excluding it before you do the calculations. In the given data, I suspect there is an ...

*December 19, 2016*

**Financial mathematics**

Is this a continuation of the post http://www.jiskha.com/display.cgi?id=1482086783 ? If it is, it would be another advantage to keep your pen name the same (except using anonymous), because otherwise tutors cannot assume continuation and have to ask for details. Is $800,000 ...

*December 19, 2016*

**Chemistry (to Alice Keign)**

morality ≠ molarity lol molarity is the fraction mass of substance contained in 1 L of solution ÷ molecular mass of the substance. Note: atomic mass of Na ~ 23 atomic mass of Cl ~ 35.5 so molecular mass of NaCl ~ 58.5 But you need to look up exact masses from ...

*December 19, 2016*

**chemistry (To Yasine)**

Your effort has a good start, shows you have an idea what's needed, but, to balance equations, you have to know what the possible products are. For example, HO and ZnCl are not known products to me. If you lookup/Google Zinc Chloride, and Hydrogen Oxide, you will find the ...

*December 19, 2016*

**math(geometric series)**

1. find the common ratio: r=T(n)/T(n-1)=12/18=2/3 2. form the general sequence (considering 18 as first term, or n=1) T(n)=ar^(n-1)=18(2/3)^(n-1) 3. solve for T(n)=18(2/3)^(n-1)=512/729 or even simpler, (2/3)^(n-1)=256/6561=(2/3)^8 Solve for n.

*December 19, 2016*

**math(geometric series)**

Sum of a geometric series to n terms with common ratio r is given by S(n)=a(r^n-1)/(r-1). 1. Form the equation: S(20)/S(10)=244 (given condition) 2. Cancel out the common factor a and (r-1). 3. set u=r^10, then r^20=r^2. 4. solve the resulting quadratic in u. 5. Back-...

*December 19, 2016*

**tangent help me maths**

To prove that L1 : 2x+5y+11=0 is a tangent to the circle C : x²+y²+2x-8y-12=0 it is sufficient to prove that the distance of the centre O of the circle C to the line L1 equals the radius of the circle. To find the centre and radius of the circle C, we complete ...

*December 19, 2016*

**physics (science)**

There is a standard formula for this: "from rest" means initial velocity = 0 or V0=0 m/s Given acceleration, a = 8 m/s² S = distance travelled = 100 m Let V1=final velocity, then the given formula is: V1²=V0²+2aS Substitute values of V0, a and S into ...

*December 19, 2016*

**Chemistry**

I do believe that the skill of transforming an actual problem to numbers is part of your training. However, I will work on this for this time. The problem can be solved by proportions. Using: "Therefore 24 g of Mg produces 2 g of H2. How many grams of H2 will be produced ...

*December 18, 2016*

**Chemistry**

The atomic mass of magnesium is 24, which means 24 grams of magnesium makes 1 mole. On the other hand, the atomic mass of hydrogen is 1, so H2 will weigh 2 grams per mole. From part A, which you correctly answered (except for the missing + sign), we conclude that 1 mole of Mg ...

*December 18, 2016*

**chemistry**

Molecular mass of propane (C3H8) = 3*12+8*1 = 44 Molecular mass of water (H2O) = 2*1+1*16 = 18 using the balanced equation, we find that the ratio mass of propane : mass of water = 1*44 : 4 * 18 = 44 : 72 Hence the mass of water can be calculated. Note: replace the above ...

*December 18, 2016*

**math (to Jose)**

hint: 5(S+15)=5*S+5*15 (distribution) =5S+75

*December 18, 2016*