MathMate
Newest questions and responses by MathMate
Precedence rules for the algebra community
Precedence of operators In simple algebra, there is a set of precedence (priority) of operations that should be respected in order that everyone evaluates mathematical expressions in the same way. Although these rules have been taught in elementary school
asked on September 2, 2014 
UOS
Pseudocode: read Capacity, MilesPerGallon MaximumRange:=Capacity*MilesPerGallon print "Maximum Range = ", MaximumRange
asked on May 17, 2014 
To Debela Duguma
Your question tucked at the end of another post was probably lost. Post the complete question as a new post if you would like help.
asked on July 23, 2013 
How to get quick responses to your math questions
Math is a wide subject, ranging from K to 11, college and university. Then there is algebra, trigonometry, geometry, arithmetic, calculus, number theory, ... etc. Not all teachers answer all math questions (many do). If you would give a little more detail
asked on May 25, 2013 
To GANDU MAN
Your geometry problem of yesterday has been answered. http://www.jiskha.com/display.cgi?id=1368886945
asked on May 19, 2013 
Cal3  to Lucy
See: http://www.jiskha.com/display.cgi?id=1330465911 for response to previous question on maximum/minimum.
asked on February 29, 2012 
To Francesca and James
I have added comments to your solution of the inclusion/exclusion problem at the end of the original post: http://www.jiskha.com/display.cgi?id=1302620150 Feel free to go back and check it out.
asked on April 13, 2011 
To DrBob222
The math symbols are very easy to make, although they are not very userfriendly. Basically, we can type the & sign, immediately followed by a # sign and then the unicode number in decimal (as opposed to hexadecimal), and terminated with a ;. For example,
asked on June 13, 2010 
French  To Anna
Mme Sra is either not available or she is working on your text. You write very well, despite a few grammatical and syntax errors many of which you could probably avoid. To get you started, I enclose a few to help you with self corrections. Do look for
asked on December 16, 2009 
Math6grade (Anonymous)
Sorry Anonymous that I deleted your post by mistake, but here's the answer to the question: "there are four posts on each side of a square fencedin are. How many posts are there in all?" The corner posts are counted for both of the adjacent sides. So the
asked on December 3, 2009 
ToGnozahsContinuation of thread
I don't know if there is a limit on the length of the thread. My posts don't seem to go in any more to: http://www.jiskha.com/display.cgi?id=1253908539 The correct formulas are: F = C*9/5 + 32 C = (F32)*5/9 The graduations are wider apart on the C scale,
asked on September 27, 2009 
test
http://www.jiskha.com/
asked on May 31, 2009

physics
Please describe what you see in the figure, because we don't.
posted on August 13, 2018 
Physics
Acceleration due to gravity: g=9.81 m/s^2 Upwards acceleration : a=2 m/s^2 Tension in cable T= 6000 N Let m=mass of elevator T=mg+ma = m(g+a) solve for m
posted on August 13, 2018 
Economics
See response to previous question.
posted on July 23, 2018 
Economics
Since it is a monopolistic product, it will be assumed everything made will be sold, and at the predicted price. p = selling price Quantity sold=quantity manufactured = q(p) =60p/2 Cost, C = 60 at all sales volumes Profit in terms of price, p P(p)=
posted on July 23, 2018 
Statistics
Assuming the worst case of the point estimate of 50% (i.e. 50% participation), and n=size of sample Margin of error = z1α * standard error of worst case point estimate = z95% * sqrt(0.5(10.5)/n) =1.96 * 0.5/sqrt(n) Equate to given margin of error of
posted on July 23, 2018 
Algebra
Using the definition of logarithms y=loga(x) .......(1a) ≡ ay = x .............(1b) Put x=11 in (1a), log(x) is understood to be base 10, so a=10, y=1.0414 [1a] 1.0414 = log10(11) By the definition of logarithms, (1a) is equivalent to (1b), so
posted on July 23, 2018 
Algebra
Assuming you mean: Given that loga(7) = 0.845, and loga(2) = 0.301, find loga(343). Using the rule of logarithm: loga(xn) = n*loga(x) .............(1) From 7^3=343, we substitute in (1) x=7, n=3, so loga(343) =loga(73) = 3*loga(7) = 3*0.845 = ?
posted on July 23, 2018 
maths
Is the question actually (note punctuation and parentheses) the following? if n varies inversely as kv/(k+v), and n is equal to 16 when k=4 v=8, find the relationship between k v and n.
posted on July 23, 2018 
Algebra
One of the rules of logarithm is log(a)+log(b) = log(ab)........................(1) This means that the logarithm of a product is the sum of the logarithms of the multiplicant and multiplier. Since 4x is a product of 4 * x Which do you think is the right
posted on July 23, 2018 
Maths
10% gives $889 after one year. 15% gives $8890*0.15=$1333.5 after one year. So the annual interest is a minimum of $889. If only $560 was earned after one year, someone got shortchanged, sorry to say.
posted on July 23, 2018 
math
Given equation: (x+1/x)²  14(x+1/x) = 72 ...............(1) Use the substitution u=x+1/x .............................................................................(1a) then (1) becomes u²  14u 72 = 0 .....................................(2) Factor
posted on June 29, 2018 
Science
In human diploid cells, there are 23 homologous sets of two chromosomes (=46). Each chromosome is composed of one DNA molecule. In the replication stage, each chomosome is duplicated into two chromatids (two DNA molecules), but are still attached by the
posted on June 16, 2018 
Math
Given: purchase price = 320,000 down payment = 8% mortgage bought down (to 6%) with 3 points (3%). Term, n= 30 years rate, i=6% per annum = 6%/12 = 0.005 compounding frequency = monthly (ASSUMED). Solution: Down payment = 8% * 320,000 = 25,600 Loan, P =
posted on May 15, 2018 
Physics
This comparison exercise provides an analogy between  water flow with electric current (electron flow)  mechanical energy (kinetic energy) with electrical potential energy  water pump and battery Please give it a try by substitution of the analogies and
posted on March 19, 2018 
Algebra
If we add up the number of jelly beans of the 10 listed students, we have 95 jelly beans. The average number being 10 for each student, and there are 10+Leo=11 students, so the total number of jelly beans is 11*10=110. Number of jelly beans Leo received
posted on March 19, 2018 
Math
Number of ways of choosing 3 distinct kinds of rolls for first guest =(3/9*3/8*3/7)*(3!) =9/28 Number of ways of choosing 3 distinct kinds of rolls for second guest =(2/6*2/5*2/4)*3! =2/5 Number of ways of choosing 3 distinct kinds of rolls for third guest
posted on February 10, 2018 
Math
We don't need the website. translation 3 units right and 2 units down follows the following rule: (x,y)>(x+3,y2) So we will need to take the coordinates of A, B and C, and transform each point according to the rule given above. For example, if P(2,5),
posted on February 10, 2018 
Math
1) After giving $5 to Greg, David has $25. Greg now has 1/5 as much as Davis does. How much did Greg start with? Now David has $25 Greg now has 1/5 of David, or 1/5 of 25, or 5. So before he got $5 from David, Greg had 55=0, or nothing. 2) if
posted on February 10, 2018 
Math
p+pq = 4(ppq) p(1+q) = 4p(1q) Since pq ≠ 0, then we can cancel out p on both sides. => 1+q=4(1q) Expand and solve for q 1+q=44q 5q=41=3 q=3/5 Check: (1+q)=1+3/5=8/5 4(1q)=4(13/5)=4(2/5)=8/5 Therefore the value of q is correct and unique.
posted on February 10, 2018 
math
Sorry the sketch did not work out! :(
posted on February 10, 2018 
math
Events: S=Laurel waits 40 minutes or less for hardy. ~S=Laurel waits more than 40 minutes. Assumptions: both arrivals are random and create a uniform probability distribution. Between 1:00 and 1:20, Laurel will be sure to wait 40 minutes or more, since
posted on February 10, 2018 
Math
Here's an example of what the question is asking for: If Molly removed 2 orange marbles, the probability of drawing an orange marble from the remaining batch is P(Orange) = (22)/(4+3+3+0) = 0/10 = 0 and that does not equal 1/5, so she did not remove 2
posted on February 3, 2018 
Math
Twenty members of a group contributed sh 80000 each means contribution from members = 20 members * 80000 =sh 1600000 They already had sh 120000 in a bank out of which sh 20000 was to remain means from bank reserve = 120000  20000 = sh 100000 Price of land
posted on February 3, 2018 
Mathematical Range.
Well, I do not know how you got the range as ± 3 to ± 11.1. The interpretation of your answer is 11.1 (excluding) to 3 (including) together with 3 (including) to 11.1 (excluding). This means that (3,3) is excluded from the range. Confirm that this
posted on February 3, 2018 
University Genetics part 2
The man has Widow's peak (Ww or WW) and attached earlobes (dd), and the woman without widow's peak (ww) and detached earlobes (Dd, the d is inherited from her father). So yes, Man: Wwdd or WWdd (could be either one) Woman: wwDd. Case 1: If man has Wwdd
posted on January 27, 2018 
University Genetics
The fact that fur colour can be tortoise means that both phenotypes are expressed, as a result of codominance of the genotypes black and orange. Since we are given that fur colour is controlled by Xlinked alleles, it means that tortoise can only be
posted on January 26, 2018 
Algorithms
Hints: Properties of the given dataset: 1. Could have a large number of nodes. 2. Generally very large and sparce. 3. Requires relatively efficient search algorithm given a node. 4. In general, contains cycles. Since cycles are present, we can safely
posted on January 22, 2018 
Math
Here we do not know the initial investment, P. We can still apply the formula to solve for it since we know the future value = $44800. From FV=44800=P(1+0.028/365)^(23*365) we solve for P P=44800/((1+0.028/365)^(23*365)) =23528.98 The interest earned is
posted on November 27, 2017 
Statistics
Use binomial distribution because: 1. Bernoulli trials (either girl or boy) 2. number of trials (n=9) known. 3. probability (p=0.5) of outcome known and remains constant throughout trials 4. trials are independent of each other. n=9 p=0.5
posted on October 2, 2017 
Math
2012 was a leap year, so 366 days. deaths per hour = 31700 deaths /(366 days *24 hour/day) = 7925/2196 deaths / hour = 3.61 deaths per hour (approximately)
posted on September 26, 2017 
Math
Yes, $17592.59, to the nearest cent.
posted on September 26, 2017 
Discrete Math
Another way to solve. Let A=# of students who answered the first question B=# of students who answered the second question C=# of students who answered the third question Then we are given B+CB∩C = 10 A+CA∩C = 14 A+BA∩B = 12 Add three
posted on September 26, 2017 
Math
inflation rate (increase) =(new valueold value)/old value =(82.472.6)/72.6 =9.8/72.6 =.134986 =13.4986% =13.50% (to the nearest hundredth of a percent)
posted on September 26, 2017 
Math
Admission = $9 charged once each ride = $2.5x (x=number of rides) Total cost for x rides =2.5x+9
posted on September 26, 2017 
Vector Calc
The equation of a spherical surface centred at (0,0,0) is x^2+y^2+z^2=r^2 centred at (x0,y0,z0) (xx0)^2+(yy0)^2+(zz0)^2=r^2 substituting C(4,5,0), the equation of the spherical surface is (x4)^2+(y+5)^2+z^2=10^2=100 Assuming zcoordinate is
posted on September 2, 2017 
Math
The given quadratic equation has no real roots when the determinant is (strictly) negative. This happens when b^24*a*cp3640=4 So the condition for f(x)=p has no real roots is when p>4.
posted on August 17, 2017 
Math
Since the 401k plan is tax free until the money is withdrawn, Sal has a 5% salary contributed to the plan AND deductible at the marginal rate of 20%. The company contribution does not matter for the current year taxes until the money is withdrawn. So the
posted on August 9, 2017 
college math
Use binomial distribution, which requires a known and constant probability of success, a known number of trials, independence of trials. probability of success, p=1/6 number of trials, n=3 the probability of x successes is P(x)=C(n,x)p^x (1p)^(nx) where
posted on August 3, 2017 
Finance
Oh yes, please add machine cost Y(0)=90000 to negative cashflows. All other calculations remain valid.
posted on August 2, 2017 
Finance
You seem to have deducted machine depreciation as 25000/3 instead of 25000/year. Also, you have provided the first year cash flow without taking into account of the WACC. I suggest you make a cashflow diagram for three years, using following information
posted on August 2, 2017 
probabilities in statistics
(a) Given a diamond dealt first (without replacement) There are 51 cards left, so 13 clubs from a deck of 51 cards: P(CD)=13/51. (b) Ace of hearts followed by a black card. P(A∪B)=1/52*26/51=1/102
posted on August 2, 2017 
To @Writeacher
Personally I do prefer the actual dates over today/yesterday because if and when we save a page, today/yesterday becomes a relative date which is ambiguous. However, today/yesterday could be an addition to the complete date to avoid confusion.
posted on July 30, 2017 
physics
For a simple pendulum, period T=2*π*sqrt(L/g) Substitute T=5T, L=4L 5T=2*π*sqrt(4L/g) => square both sides and solve for g: 25T=4π²(4L)/g g=16Lπ²/25T where L and T are as given in the question.
posted on July 30, 2017 
Math
Your solution: (5!*7*6*5*4)*(3*2*1)+7!*5!*2!*2! =604800+2419200 =3024000 The first term is basically 5!7! which is the number of ways each gender can be permuted separately, and I agree with that, however they are seated. Now coming to the restriction,
posted on July 30, 2017 
probability
Event: S=success for last passenger to get his assigned seat. 1=case 1 2=case 2 Note that cases 1 and 2 are complementary. Case 1: P(1)=1/100 If the first person chose (randomly) his assigned seat Then all the rest of the passengers will also get their
posted on July 15, 2017 
Finance
i=10.5%=.105 n=2 for machine J, =3 for machine K We assume machine J lasts 2 years with no salvage value, same for machine K, but three years. Case J: PV=110001200/(1.105)1300/1.105^2= =13150.65 annual expense over 2 years A=P*(A/P,10.5%,3)
posted on July 15, 2017 
Math
Approximate the earth as a perfect sphere, with radius 6371 km. Change in longitude = 6020 = 40° = 40π/180 radians Latitude of flight path = 20° N horizontal radius = Rcos(20°) Horizontal arc length from A to B =Rcos(20°)(40π/180) =6371*0.9397*.6981
posted on July 14, 2017 
geometry
Given: D (2,2), E (2,1), and F (3,5). The reflection about the yaxis follows the following rule: sy: (x,y)>(x,y) For example: sy: D(2,2)>D'(2,2) The translation along a vector (p,q) follows the following rule: T(p,q): (x,y)>(x+p, y+q) Example:
posted on July 14, 2017 
Finance
The given information assumes that the investment is made on the 31st of December (end of year of year of investment), so year 0. At the end of year 3, the NPV is 879.46, and at the end of year 4, the NPV is +2907.51 as you had it. I believe payback
posted on July 14, 2017 
maths
if the prime factors of p²+1, excluding 1 and itself, are of the form {a²,b  a≠b}, then the possible factors are: {1,a,b,a², ab, a²b} total exactly 6 factors. The first few such sums are: 1²+11=12=2²*3 [but 1 is not a prime] 3²+11=20=2²*5
posted on July 14, 2017 
maths
When more than two (i.e. 3 or more) lines intersect at the same point, i.e. they intersect each other, these lines are concurrent.
posted on July 14, 2017 
math
Let interest be i per annum simple interest. 4050(1+i*2)=4526.50 solve for i. 1+i*2=4526.5/4050=1.117654321 i=(1.1176543211)/2 =0.058827 1 lakh = 100,000 So after 3 years, accumulated amount =100,000(1+3i) =100,000(1.1764815) =117648.15
posted on July 13, 2017 
math
We know (assume) that each cow and chicken has one head. Chickens have 2 legs and cows have 4 legs. If there are C cows, then there are 30C chickens. Count total number of legs 4C+2(30C) = 86 Simplify and solve for C 4C2C=8660 2C=26 C=13 So there are
posted on July 13, 2017 
maths
If long diagonal is defined as continuous diagonals with 8 squares, then there are only two. The following scheme should work. C C _ _ C C _ _ _ _ C C _ _ C C C C _ _ C C _ _ _ _ C C _ _ C C C C _ _ C C _ _ _ _ C C _ _ C C C C _ _ C C _ _ _ _ C C _ _ C C
posted on July 13, 2017 
software development
array length syntax is different for different languages. Please specify language you're using. most use the syntax len(array), or variants.
posted on July 12, 2017 
Physics
dx/dt=2t, integrate, x=t^2+Cx dy/dt=4, integrate, y=4t+Cy We know x(0)=y(0)=0 => Cx=Cy=0 The trajectory of the particle is therefore Guess you can find displacement at t=2 with the above information.
posted on July 12, 2017 
Physics
You don't have to worry about the top, just assume that it was off balance by some random motion, and acceleration will start from there where KE=0, and PE=mg(R) if we take reference elevation at the centre of the sphere. Then at at certain θ
posted on July 12, 2017 
Physics
Try reaction=centripetal force, mg(cos(θ))=mv^2/R Yes, v^2 (at the time it leaves sphere) can be calculated using energy considerations.
posted on July 11, 2017 
spatial reasoning
I find 8.  = = = = == == ==
posted on July 11, 2017 
math
Assuming the order within the day does not matter. Monday: 15C3 ways Tuesday: 12C3 ways Wednesday: 9C3 ways Thursday: 6C3 ways Friday: 3C3 ways Total= product of the above numbers, =455*220*84*20*1 =168168000
posted on July 10, 2017 
math
The rectangle is slanted with respect to the axes. Make a sketch to see if the corners are in order. You can use the graphing tool desmos.com to help you plot. From the plot, it looks like the three points A, B and C do not form any rightangle, so there
posted on July 10, 2017 
math
Try pairing numbers to make a sum of 9, after taking out, say 1 and 4 for the first digits. leaves 2,3,5,6,7,8, so pair 2,7, 3,6, 5,8 for the other digits. making 1235 and 4768 sum is 6003. Try other combinations to see if it is possible to get closer.
posted on July 10, 2017 
Physics 11
(a) Normal force, N= 140g N μs=0.25 frictional force to move crate = μN = 0.25*140g = 343.35 Assuming force of 340N is acting horizontally, crate will move since 390N > 343.35 N (b) μk=0.17 kinetic frictional force = μkN = 0.17*340*9.81 = 233.48 N Net
posted on July 10, 2017 
physics
Volume of object = 40*30*10=12000 cm³ Principle of floatation says that the mass of liquid displaced by a floating object equals the mass of the object. (C.F. Archimedes) For a density of 0.92 g/cc floating on a liquid of density 1.0 g/cc, the mass of
posted on July 9, 2017 
math
Integer is the set of all numbers without the need to use decimals or fractions, examples, 2,100,0,4. Counting numbers are positive integers, examples: 1,2,10,10000, etc. Counting numbers are called natural numbers by mathematicians. Depending on the
posted on July 8, 2017 
Physics
There is probably a more elegant way to solve the problem, but here's one that works. We know a and b are unit vectors. By the cosine rule, we can find the angle between the two vectors a+b as: cos(φ)=(1^2+1^2(√3)^2)/(2*1*1)=1/2 => φ=2π/3. Without
posted on July 8, 2017 
Science
49g in 100 mL solution => 490g in 1000 mL solution. molecular mass of H2SO4=2+32+64=98 Molarity = (mass/L)/molecular mass = ?M
posted on July 8, 2017 
MATH
Finance charge = average daily balance*interest rate Here average daily balance = 250.82 interest rate = 1.7% = 0.017 Finance charge = 250.82*0.017 = ?
posted on July 7, 2017 
b e t Sofia high school (arethametic)
Let the AP be a(n)=a(0)+(n1)d then we were given a(p)=q => a(0)+(p1)d=q a(q)=p => a(0)+(q1)d=p Subtract one equation from the other a(0)a(0)+(p1(q1))d=qp simplify (pq)d=qp solving, we find that d=1 substitute d and p in the AP a(p)=a(0)+(p1)d
posted on July 7, 2017 
engineering
Check if you are using these formulas for pressure and temperature. If so, go ahead and feed your calcxulator. If not, please post formulas you use. https://en.wikipedia.org/wiki/Barometric_formula You may post your answers for checking if you wish, but
posted on July 7, 2017 
Mathematics question
In summary, 90% of cats and 10% of dogs think they were cats. So if the population is made up of C cats and D dogs, then (0.9C+0.1D)/(C+D)=0.2 Let x=C/(C+D), then D/(C+D)=1x 0.9x+0.1(1x)=0.2 isolate x and solve 0.9x0.1x=0.20.1 0.8x=0.1 x=0.125 => 12.5%
posted on July 7, 2017 
Biology
Codominance means both are expressed in the presence of each other. If there is one allele of each, then both A and B will be expressed (giving AB type). If either an A allele is paired with a different one, such as O, then the dominance is expressed and
posted on July 7, 2017 
Math
A=biannual payment = 12,000 APR=10% => i=10%/2=0.05 n=number of periods (each sixmonths) = 10*2=20 Present value P=A*((1+i)^n1)/(i(1+i)^n) You can substitute values and compute. P is the same as the amount borrowed in a mortgage with a semiannual
posted on July 7, 2017 
math
Assuming there is no limit on the size of the individual pieces, e.g. NOT x pieces of equal area. No cut: 1 slice 1 cut: 2 slices 2 cuts: 4 slices (last cut intersects one previous cut, so adds two pieces) 3 cuts: 7 slices (last cut intersects 2 previous
posted on July 7, 2017 
MATH 123
Use amortization equation for monthly payment = A =P*i*(1+i/12)^(12n) / [(1+i/12)^(12n)1] P=amount borrowed (present value) i=annual interest rate n=duration of loan in years compounding frequency = 12 times per year. Case 1: P=23000 i=4.6% = 0.046 n=3
posted on July 6, 2017 
maths
P1=300/(1.12^3)=213.53 P2=1000/(1.12^5)=567.43 P3=200/(1.12^15)=36.54 (negative because money is due in the future)
posted on July 4, 2017 
maths
i=0.12 use P=F*(P/F,i,n)=F/((1+i)^n) P1=300/(1.12^3)=213.53 P2=1000/(1.12^5)=567.43 P3=200/(1.12^15)=36.54 (negative because money is due in the future) P=P1+P2+P3 [present value]
posted on July 4, 2017 
quantitative apptitude
Since the period of time is not mentioned, it will be assumed that it is a perpetual annuity, with initial sum S generating interest of $1200 per month forever. 18% APR = 1.5% per month. Therefore S*0.015=1200, or S=1200/0.015=80000
posted on July 3, 2017 
Math
Each test is graded in R=(3 teachers * 3 hours)/ 40 tesets =9/40 teacherhour/test 480 tests will require Time=480 tests *R =480* (9/40) tests*teacherhours/test =108 teacherhours. 12 teachers will take Time = 108 teacherhours / 12 teachers =108/12 hours
posted on July 3, 2017 
MATH
Again here the keyword is "among" 10 people. Check that the conditions of binomial distribution are satisfied (ref. the airplane problem). Then proceed with the calculation of "at least two" out of 10, namely "not zero", "not one" out of 10. Instead of
posted on July 3, 2017 
math
The situation calls for binomial distribution because all criteria are satisfied: 1. Bernoulli trials (i.e. either success or failure, one of exactly two outcomes). 2. Probability of success (i.e. failure of engine) is known (p=0.004) and remains constant
posted on July 3, 2017 
math
P(7
posted on July 3, 2017 
physics
Let xaxis => due east yaxis => due north then 100m due east and 50m due north => New position P(100,50) distance by Pythagoras, D=sqrt(100^2+50^2) angle (from xaxis)= tan1(y/x)=tan1(50/100)=tan1(1/2) [ in the first quadrant]
posted on July 2, 2017 
probability
Question asks P(2 red), so Probability of first red=6/10 Probability of second red = (61)/(101)=5/9 By the multiplication rule, P(2 red) =6/10*5/9 =30/90 =1/3
posted on July 2, 2017 
probability
Probability = P(2 red)+P(2 blue) =6/10*5/9 + 4/10*3/9 =(30+12)/90 =7/15
posted on July 2, 2017 
math
You're welcome!
posted on July 2, 2017 
math
With two inequalities, you can have a maximum of one intersection point. The feasible region is therefore open. The feasible region is below the red line, and above the black line. The corner point has already been found correctly, ... by you!
posted on July 2, 2017 
Business Math
Amount to save = 10,0002500=7500 Use the future value formula: A=F*(A/F,0.08,3) =F(i)/((1+i)^n1) =7500*0.08/(1.08^31) =2310.25 Note: each payment is even less than 7500/3=2500 because the first two payments earn interest at 8%.
posted on July 1, 2017