Tuesday

July 7, 2015

July 7, 2015

Total # Posts: 11,301

**math**

Lateral surface of a cylinder Al=2πr*h where h is measured along the axis of the cylinder. When the rectangle is rotated along it's length, then h=length, r=width. When the rectangle is rotated along it's width, then h=width, r=lengh. So you can calculate the ...
*July 21, 2013*

**Math<Please Help>**

Simple way: Multiply the planar area (25m*12m) by the average depth of (1+4)/2=2.5m to get volume= 750 m³. Calculate the area of the trapezoid which is obtained by cutting a vertical section along the length: 25*(1+4)/2. Multiply the above by the width of 12 m to get the ...
*July 21, 2013*

**Math**

Computers actually use binary number systems, since a switch can either be on or off. However, contents of computer memory is more concisely represented by octal and hexadecimal representations because 1. they are easy to convert to and from binary system 2. they are condensed...
*July 21, 2013*

**GCSE Physics**

Energy paid for =30/0.15=200 KWH Number of hours for boiler = 200 KWH / power of boiler The number of hours will not be know until the power of the boiler is known.
*July 20, 2013*

**math**

Q4c: 1/x^2*x*sqrt(x)*sqrt(sqrt(x))=a^c; 1/x^(1/4) = a^c x=a^(-4c) For: log5(5-4x)=log√5(2-x) log5(5-4x)=log5(2-x)² 5-4x=(2-x)² x=±1
*July 20, 2013*

**physics**

Volume of liquid =3.57*10^-4 m^3 =357 ml mass of liquid =357 g mass of aluminium (can) =421-357 =64 g density of aluminium = 2.7 g/ml Volume of aluminium = 64/2.7 cc = 23.7 cc
*July 20, 2013*

**geometry**

I am sorry about the incorrect designations. However, the same process can be used to solve for CP=3, although the result would be different. It seems to me that Steve's method is simpler, so use his method. Using Newton's method to solve for a non-linear equation f(x...
*July 20, 2013*

**geometry**

First draw the square ABCD and indicate a point P inside the square near the side AB about 1/3 from A to B. Label the lengths AP=1, PB=2, PD=3, and each side of the square s. Join BD and mark the length (√2)s. Label ∠APB as α, ∠DPA as β. Consider each ...
*July 20, 2013*

**Statistics**

The following reference may confirm your assumptions. http://cjasn.asnjournals.org/content/3/5/1246.full
*July 19, 2013*

**MAT LAB**

For 9_3, the question is not clear because we do not see the accompanying figure. However, on examining the data, it seems probable that the two "walls" (meaning no strain/movement along that direction) are in the y-direction, which means that εy=0. From the ...
*July 19, 2013*

**MAT LAB**

Note: Equations (A), (B) and (C) may be used to solve problem 9_2_1, namely Lx=L(1+εx),... Watch the signs of the stresses.
*July 19, 2013*

**MAT LAB**

Note that 1/20 is a relatively large strain and the above equations are approximate to first order and may not be accurate for large strains. Use the relations: εx=[σx-ν(σy+σz)]/E ....(A) εy=[σy-ν(&sigmaz;+σx)]/E ....(B) &...
*July 19, 2013*

**MAT LAB**

9_1_1 Recall that for an isotropic material, when σx is applied on a material of modulus of elasticity E, then the strains are: εx=σx/E from which e can be calculated. Since εy=-νσx/E, and similarly εz=-νσx/E, we are able ...
*July 19, 2013*

**Calculus**

This is a project you need to do using Mathematica. I suggest you go ahead and actually learn to use Mathematica to solve the above problems. If you have doubts and would like to check you results, you are welcome to post them for a check here.
*July 19, 2013*

**math**

Yes, 2655 in³.
*July 19, 2013*

**math**

Calculate volume of locker V=L*W*H Calculate volume of books (given) B=1545 in³ Calculate volume left =V-B
*July 19, 2013*

**Math**

The volume to be integrated is bounded by the planes 0≤x≤2 0≤y≤2 z=0 and the surface z=16-x²-2y². Thus the volume is given by the triple integral: V=∫∫∫z dz dx dy Where z is evaluated from 0 to 16-x²-2y², x and y are both evaluated ...
*July 19, 2013*

**math**

The rule for converting from metres to centimetres is that one metre equals 100 centimetres.
*July 18, 2013*

**Solution Set**

{x+y=3 ............(1) {-3x+2y=-19 ...........(2) Solve by elimination. Multiply (1) by 3 and add to (2) in order to eliminate x: 3x+3y=9 ..........3(1) -3x+2y=-19 .......(2) Add together 0x+5y=-19+9=-10 Solve for y: y=-10/5 = -2
*July 18, 2013*

**Calculus**

If you need help with finding the standard forms of the particular solution, check your course notes, your textbook, or the following link: http://tutorial.math.lamar.edu/Classes/DE/UndeterminedCoefficients.aspx
*July 18, 2013*

**Calculus-ODE**

Start with solving for the complementary solution to the homogeneous equation 2y"+3y'+y=0, the characteristic equation is 2r²+3r+1=0 which is an algebraic equation which can be factorized into (2r+1)(r+1)=0 or r={-(1/2), -1} The complementary solution is ...
*July 18, 2013*

**math**

Proportions: 100% : 1.75 hours x% : 1 hour x=1*100%/1.75
*July 16, 2013*

**math**

Use time = 1/(1/M+1/R)
*July 16, 2013*

**math**

2=1/(1/6+1/B) => B=1/(1/2-1/6)=3
*July 16, 2013*

**math**

1/(1/20+1/30+1/10) =60/11 minutes
*July 16, 2013*

**math**

1/(1/6+1/5.5+1/2.2) =1.245 DAYS
*July 16, 2013*

**algebra**

√(75) =√(25*3) =√(5²*3) =5√3
*July 16, 2013*

**math**

2³=?
*July 16, 2013*

**gen physics**

The centre of gravity is located at a point such that the product of mass multiplied by the distance to the C.G. is equal, namely: Let x = distance from mA, then 50-x = distance from mB. mA*x = mB(50-x) solve for x, and hence 50-x.
*July 16, 2013*

**gen physics**

apparent ρ=7860-1000=6860 kg/m² Tension in wire =apparent weight =apparent mass*g =(0.154³)*6860*9.81 N =246 N (approx.)
*July 16, 2013*

**physics**

ω2=ω1)+angular acceleration*time or time = (ω2-ω1)/angular acceleration =(0.28-0)/0.021 =40/3 sec.
*July 16, 2013*

**Math**

Please comment on the previous answer before reposting: http://www.jiskha.com/display.cgi?id=1373921871
*July 16, 2013*

**math :)**

You're welcome. :) The method above is correct, but the final result should be 2 7/24 lbs, since 2*24=48, and 55-48=7. Sorry for the oversight.
*July 16, 2013*

**math - addition of fractions**

The question requires us to add three fractions, with different denominators. The first step is to find a common denominator which is the LCM (least common multiple) among 3,4 and 8. Since 4 divides 8, so 4 need not be accounted for. The LCM of 3 and 8 is just the product 24, ...
*July 16, 2013*

**Geomtry**

I have a different interpretation of the problem. If I were to assume "three sides" as one length (parallel to the canal) and the two other sides perpendicular to the canal, then we are only fencing three sides on land, and the fourth side is bounded by the canal. ...
*July 16, 2013*

**math**

240.75 is correct.
*July 16, 2013*

**Math**

From the knowledge of divisibility, we know that 2 is a factor (all even numbers). That reduces 2002=2*1001 Again, the difference of sums of alternate digits equals zero (1+0)-(0+1)=0, so it is divisible by 11. That makes 2002=2*11*91 We should (try to) know all prime ...
*July 16, 2013*

**Math**

She cannot subdivide the equilateral triangle into 2 isosceles triangles. This is the smallest N which is impossible. She can subdivide it into 3 congruent isosceles triangles by joining the centroid with each of the vertices. Each triangle is then 30-30-120 as angles. Each of...
*July 15, 2013*

**Calculus**

The idea is to find the family of lines perpendicular to L:7x+5y-2=0. Out of that, we find the particular line L1 passing through P(-6,-2). The intersection of L and L1 gives the required point (closest to P). Family of lines perpendicular to L passing through P0(x0,y0): L : ...
*July 15, 2013*

**Statistics**

With replacement, the probability of selecting a good apple stays at 60/80=3/4. For a two-step experiment, the probability is the product of individual steps, hence, probability of select a good apple in each pick is (3/4)^2=9/16
*July 15, 2013*

**maths**

Two trains with speeds s and s+5 km/hr. Initial distance=340 km final distance = 30 km Total distance travelled = 340-30=310 km Total speed = s+s+5=2s+5 Time = 2 hrs Form equation equating distance travelled Time*speed=distance, or 2(2s+5)=310 2s+5=155 2s=150 s=75 Speeds of ...
*July 15, 2013*

**French**

"J'ai faim" is the proper expression to say "I am hungry." Just like in English we would not say "I am hunger", it would be incorrect say the equivalent in French. Another notable difference in French from English is about age. We would say &...
*July 15, 2013*

**object oriented programming**

Can you show us your pseudocode as a start?
*July 14, 2013*

**trig**

Parentheses are assumed missing. Implied parentheses are ALWAYS required in numerator and denominator of fractions. (cos^2x+sin^2x)/(cot^2x-csc^2x) This problem can be solved by converting all functions in terms of sine and cosine according to the standard definitions. (cos^2x...
*July 14, 2013*

**Java programming- simulation of rolling dice**

You have made the arrays die1...die4 to do two things: 1. as a counter (accumulator) for the frequency, and 2. as the value of the face. This is an impossible task, and that explains why the total adds up to more than a million. I suggest you make the following changes: 1. Add...
*July 14, 2013*

**Elementary mechanics**

Use the kinematics equation: Vf=Vi+at where Vf=final velocity=i-2j (m/s) Vi=initial velocity, yet unknown a=acceleration=F/m (in vector form) t=time=10 s a=(2i+7j)/5=0.4i + 1.4j Vf=(i-2j)+(0.4i+1.4j)(10) =(i-2j)+(4i+14j) =5i+12j
*July 14, 2013*

**Computers C++**

What are your thoughts?
*July 14, 2013*

**GEOMETRY (SA oftriangular pyramid)**

In the calculations of surface area of a pyramid, the height is not required if the apothem (slant height) is given. The height is required, however, to calculate the volume of a pyramid. In fact, the height h is not consistent, because h should always be less than the slant ...
*July 14, 2013*

**GEOMETRY (SA oftriangular pyramid)**

Lateral surface area =perimeter of base * apothem /2 =3b*s/2 (for a regular pyramid with a triangular base) Area of triangular base with side b =(√3)*b/2*(b/2) =(√3)b²/4
*July 14, 2013*

**math:units conversion**

Convert 6 cm to mm = 60 mm. Now add 60mm to 4 mm to get your answer.
*July 14, 2013*

**Math**

If each team plays with each of the other four teams N times, then the number of games played would be: 4, 8, 12, ... Can you find which of the five numbers does not belong?
*July 13, 2013*

**College Algebra**

Start with (x-(-1/6))(x-(-8/9))=0 Multiply by 54 on both sides to get (6x+1)(9x+8)=0
*July 13, 2013*

**trig**

Convert all three functions in terms of sine and cosine, hence simplify.
*July 13, 2013*

**statistics**

Possible typo in bold: "Playing game of chance and pay 300 by rolling a fair die one time if you rome a 2 and receive $1300 if you roll a 4 or six you receive $900 if you ore a 3 5 or one receive nothing. find expected value for this game. based on value is it a good game...
*July 13, 2013*

**statistics**

Binomial distribution: - large population=>probability is (almost) constant - p=0.5 (men) q=(1-0.5) (women) - random independent multiple trials N=9 - 2 possible outcomes at each trial P(7)=C(9,7)*p^7 * q^2 =(9!/(2!7!))*0.5^7*(1-0.5)^2 =0.07 (approximately)
*July 13, 2013*

**Calculus**

See: http://www.jiskha.com/display.cgi?id=1373656357
*July 12, 2013*

**Linear Equation**

Let x=number of gallons of regular sold then 220-x=number of gallons of premium sold Total receipt: 2.20x+2.70(220-x)=519 Solve for x.
*July 12, 2013*

**Math :)**

You're welcome!
*July 12, 2013*

**Math**

x=(5±(√15)*i)/2 If you do not expect complex roots, please check for typos in the original question.
*July 12, 2013*

**Math**

x/(x-2) + (2x)/[4-(x^2)] = 5/(x+2) This calls for finding the common denominator, and then solving for x using the numerators. Do not forget to exclude the asymptotes values of x where the denominator becomes zero. LCM (lowest ommon multiple) of denominators (x-2), (4-x²...
*July 12, 2013*

**algebra1 HELP PLEASE Thanks you!!**

y=√(64*25)=√(40²)=40 f.p.s.
*July 12, 2013*

**algebra1 HELP PLEASE Thanks you!!**

Not sure if there is a typo in your question, the speed is y(x)=5√(x)=5√(25)=25 This corresponding an equivalent acceleration approximately that of Mars.
*July 12, 2013*

**maths**

18+0.5+2.5=?
*July 12, 2013*

**maths**

The idea is to convert f(x)=asin(x)+bcos(x) into the form g(x)=k*cos(a+φ) where k and φ are constants dependent on a and b. This way, it is easy to show that the max/min values of the f(x) is ±k. Start with expanding g(x) using compound angles. g(x) =k(cos(&phi...
*July 12, 2013*

**Maths**

See: http://www.jiskha.com/display.cgi?id=1373620166
*July 12, 2013*

**Math**

First find the rule of the parabola: We know that the parabola curves (is open) towards the bottom, so the rule is y(x)=b-ax² if we set the y-axis to cut the vertex. Since y(0)=16=b, so b=16 or y(x)=16-kx² Also, y(4)=0 tells us that k=1, or the rule of the doorway is...
*July 11, 2013*

**alg2 check?**

Remember that ^ has higher precedence than * or +, so in these expressions, parentheses are required: 1. (2)(3)x^(1+3) =6x^4 2. (4)^3 x^(1*3) y^(2*3) =64 x^3 y^6
*July 11, 2013*

**Math.**

Two step experiment: multiply the probability of each step. A. P(Jeans,t-shirt)=0.3*0.6=0.18 B. P(jeans, ~t-shirt)=0.3*(1-0.6)=0.12
*July 11, 2013*

**Math- important!!!**

Use binomial distribution, p=0.28, q=(1-0.28)=0.72 A) n=5 P(3/5)+P(4/5)+P(5/5) =3C5*p^3*q^2 + 4C5*p^4*q^1 + 5C5*p^5*q^0 =10(0.28^3)(0.72^2) + 5(0.28^4)(0.72) + 1(0.28^5)(0.72^0) Use your calculator to find the answer for (A) B) Expected value for binomial distribution with n=...
*July 11, 2013*

**physics**

150 * 2*3600 j + 250 * 10*60 j =1230000 j =1.23 Mj
*July 10, 2013*

**differential calculus**

Intuitively, the circle has a bigger area for the same circumference, so we try to make a bigger circle. Also, since the area increases as the square of the circumference, we want to make 1 single shape as opposed to two. So intuitive answer is to make the smallest square ...
*July 10, 2013*

**French**

Each country name has a gender and a number. The country France is feminine singular, as demonstrated by the phrase "Vive la France!" The country United States (Les États-Unis) is masculine plural. For feminine country names, we use the preposition "en&...
*July 9, 2013*

**math**

The question does not give the required context. Some countries charge sales tax on labour, and some may not. I believe Overhead rate would be added to the labour, meaning that for every $12 paid to the worker, the customer pays $12(labour)+$15(overhead)=27. If sales tax does ...
*July 9, 2013*

**Computer Programming**

Your code seems to be in reasonable shape, except that it does not yet implement the algorithm to find the maximum revenue. So the current revenue is 600*50=30,000$ a month. Your program will increase the rent by $40 steps and recalculate the revenue. When the revenue starts ...
*July 9, 2013*

**MATH:( Base systems?!**

Divide the number by the base and note the remainder on the right. The digits from bottom to top is the number required. Example: Find 37 to base 5. 37 R 2 (37/5=7 R2) 7 R 2 (7/5=1 R2) 1 So the number is 1225
*July 9, 2013*

**Number and Operations**

3,6,9 and 18, since 20/18 also has a remainder of 2.
*July 9, 2013*

**math**

The question should have read: There are 35 students in a class who stu dy either art, music or both. 15 study art. Twice as many students who study art study music. COMPLETE THE VENN DIAGRAM TO SHOW. 35 students in all 15 study art 2*15=30 study music so 35-30=5 study only ...
*July 9, 2013*

**Math 17 Synthetic Division**

Showing steps of synthetic division requires lining up many numbers vertically, which is impossible to do at this web site. I suggest you refer to examples of sites which can format number displays. Try for example: http://www.purplemath.com/modules/synthdiv.htm
*July 9, 2013*

**GEOMETRY LATERAL AND SURFACE URGENT (PLEASEHELP)**

Total surface area of a rectangular box =2(lw+wh+hl) where l,w,h=length, width and height respectively. Total surface area of a cubical box (all sides equal to "a" =6a² Total surface area of a Rectangular prism : see above for rectangular box
*July 9, 2013*

**Math**

solid: square pyramid height, h = 15 side of base, s = 5 Area of base, Ab=5^2 area of cross section at height y =Ab*(y/15)^2 Volume (using the general solid integral formula based on Simpson's rule) V=(Area at top + Area at base + 4*area at mid-height)*height/6 =(0+25+4*6....
*July 9, 2013*

**Prisms**

See: http://www.jiskha.com/display.cgi?id=1374407375
*July 9, 2013*

**Number System**

Subtraction is done as in decimal, one digit at a time from the right. Borrow from the left digit if necessary. If the result is expected to be negative, reverse the subtraction (to get a positive difference) and then change the sign. Example: 1101 -0110 ----- 0111
*July 9, 2013*

**Number System**

Not sure if the question was quoted properly, because the last group of the first number has only three digits. To add two binary numbers, we add a digit at a time just like in decimal, using the following rule: 0+0=0 0+1=1 1+0=1 1+1=0 with a carry of 1 So to add 101 to 111 we...
*July 9, 2013*

**Number System**

You can convert too hex from binary by grouping, from the right, four digits at a time: 1 1011 1011 and convert each group from binary to a decimal digit, using A for 10, B for 11...and F for 15. For example, 1011=> 8+0+2+1=11=>B so the above example becomes 1BB in hex.
*July 9, 2013*

**Computer Programming**

I suggest you give it a try and post any difficulties you encounter. Programming is not as hard as it seems once you get started.
*July 8, 2013*

**Math**

Width = x inches (given) Length = 2x inches(given) Height = 5 inches (given) Volume = 5*x*2x = 10x² in.3
*July 8, 2013*

**Math (please help me Steve)**

Here's a lower bound solution. You may want to investigate other possibilities. The number 7 can be partitioned into 3 ascending non-negative integers in 8 ways, namely: 007# 016 025 034 115# 124 133# 233# There are 3 permutations of partitions (indicated #) with non-...
*July 8, 2013*

**Math**

Both, in a minute and in an hour. The LCM of 3, 5 and 10 is the same as the LCM of 3 and 10 because 5 divides 10 (5 is a factor of 10). The LCM of 3 and 10 is 30. So the soonest the will flash together is 30 seconds.
*July 8, 2013*

**Vba**

First, the concept of sub programs is to isolate a particular calculation and make a "black box" which returns a "complicated" answer without having to worry about how it is done. On the other hand, the UI (user-interface) belongs to a separate element of ...
*July 8, 2013*

**math**

15 2's = one way 10 2's + 2 5's = 12!/(10!2!) ways 5 2's + 4 5's = 9!/(5!4!) ways 6 5's = one way Total=194
*July 7, 2013*

**Calculus**

Think of f(x)=f1(x)+f2(x) where f1(x)=x f2(x)=-cos(x) We note that f1(x) is monotonically increasing throughout [-π, π) while f2(x) is increasing between [-π, 0) and decreasing between [0,π). Therefore to find the absolute maximum and minimum, we only need to check...
*July 7, 2013*

**Statistics/Probability**

The sum P(RR)+P(PP)+P(SS)=0.3288 which rounds to 0.33.
*July 7, 2013*

**Statistics/Probability**

A is correct. I assume you know that rock wins over scissors, paper wins over rock, and scissors wins over paper. For the other parts, make a tree diagram complete with corresponding probabilities and sum all the appropriate outcomes to get the probability. Example: R=rock, P=...
*July 7, 2013*

**math**

Let x=length of one of the equal sides. Then 42=16+x+x Solve for x.
*July 7, 2013*

**Math**

Z1=(2-5.5)/3.5=-1 Z2=(9-5.5)/3.5=+1 Look up the normal distribution table to find P(Z1<Z<Z2)
*July 7, 2013*

**physics**

Wavelength = Speed/frequency Speed of light: 3*10^8 m/s Frequency = 3*10^9 Hz Wavelength = 3*10^8/(3*10^9) = 0.1 m = 10cm
*July 7, 2013*

**heeeeeelp math**

Not too sure the point of the question, but here's the answer anyway, assuming b and c are given but unknown constants. To find (max|f(x)|) for x∈[-10,10]: Complete squares to get f(x)=(x+b/2)²+c-b²/4 where (-b/2, c-b²/4) is the vertex. If -b/2 ∈...
*July 7, 2013*

**heeeeeelpm math**

Continued from http://www.jiskha.com/display.cgi?id=1373027417 Can you show an idea of your probability tree to make sure that your interpretation corresponds to what was asked? What did you get for your answer?
*July 7, 2013*

**(pls help) physics**

Q1 1kg = 1000 g It does not make sense to use a bucket of 1.5kg to pull up 10 g of water. You must mean 10 kg of water. 1.5kg+10kg=11.5 kg Work done = mgh (in consistent units) =11.5*9.8*8 j Q2 The word "average" has been used very vaguely. If it means to calculate ...
*July 7, 2013*

**physics**

Displacement = "distance" due north (requires speed and direction)
*July 7, 2013*