# MathMate

Popular questions and responses by MathMate
1. ## 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

3. ## 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

4. ## UOS

Pseudocode: read Capacity, MilesPerGallon MaximumRange:=Capacity*MilesPerGallon print "Maximum Range = ", MaximumRange

5. ## 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.

6. ## Cal3 - to Lucy

See: http://www.jiskha.com/display.cgi?id=1330465911 for response to previous question on maximum/minimum.

7. ## 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.

8. ## To DrBob222

The math symbols are very easy to make, although they are not very user-friendly. 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,

9. ## 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

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 fenced-in are. How many posts are there in all?" The corner posts are counted for both of the adjacent sides. So the

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 = (F-32)*5/9 The graduations are wider apart on the C scale,

12. ## test

http://www.jiskha.com/

1. ## Physics

The specific gravity of Hg is 13.6. So to translate the -10 mm Hg to water, we multiply -10mm by the specific of Hg to get -10mm*13.6= -136mm water.

posted on December 22, 2019
2. ## physics

if ur reading this ur hella dumb useless person

posted on March 10, 2019
3. ## math

Second line in example should read: 8(other numerator) * 6 (this denominator) = 48

posted on January 4, 2019
4. ## math

Another way is to cross multiply. Multiply one numerator by the denominator of the other. Repeat for the other numerator. If the products are equal, they're in proportion. Example: 4/6 : 8/12 4(numerator) * 12 (other denominator) = 48 8(other numerator) *

posted on January 4, 2019
5. ## biology

Comparing families 1 and 2 allows us to make a hypothesis that it is a case of dominant/recessive, which can be confirmed with families three and four. Feel free to propose a scenario for discussion.

posted on January 2, 2019
6. ## Biology

The meninges consists of three layers, dura mata, arachnoid mater and pia mater (innermost). Together, the layers fulfull all four functions of protecting the nervous system from traumas by filling the space with cerebrospinal fluids. Blood vessels and

posted on January 2, 2019
7. ## Biology

The spinal accessory has long been considered cranial #11 (out of 12). Lately there have been debates on this though.

posted on January 2, 2019
8. ## Biology

Regarding : "but didn't feel like typing that much work." I consider a proper answer related to Punnett squares should indicate the genotypes and interpret them in terms of phenotypes, whether asked for explicitly or not. Again, I consider that as a part

posted on January 2, 2019
9. ## MATH

To Nameless: In case you have not yet verified, the fourth one should read y = -(x-3)^2 + 5 in order to have the vertex at (3,5). Suggest you post your attempt for the fifth.

posted on January 2, 2019
10. ## Biology

I guess it is part of the exercise to test knowledge of the well-known sex-linked traits.

posted on January 1, 2019
11. ## Biology

continued: (where Xx is the carrier mother, xy is the normal father) Outcomes (each 25%) Xx = daughter is a carrier xx = daughter is free from hemophilia Xy = son had hemophelia xy = son is free from hemophelia

posted on December 31, 2018
12. ## Biology

To answre this question, we need to know a few facts about hemophilia. It is an X-linked recessive defect, which means that it is present only on the x-chromosome, and in females, which has 2 x-chromosomes, will require both copies to be defective to have

posted on December 31, 2018
13. ## physics

Please describe what you see in the figure, because we don't.

posted on August 13, 2018
14. ## 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
15. ## Economics

See response to previous question.

posted on July 23, 2018
16. ## 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) =60-p/2 Cost, C = 60 at all sales volumes Profit in terms of price, p P(p)=

posted on July 23, 2018
17. ## Statistics

Assuming the worst case of the point estimate of 50% (i.e. 50% participation), and n=size of sample Margin of error = z1-α * standard error of worst case point estimate = z95% * sqrt(0.5(1-0.5)/n) =1.96 * 0.5/sqrt(n) Equate to given margin of error of

posted on July 23, 2018
18. ## 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
19. ## 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
20. ## 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
21. ## 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
22. ## 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 short-changed, sorry to say.

posted on July 23, 2018
23. ## 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
24. ## 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
25. ## 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 14, 2018
26. ## 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
27. ## 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
28. ## 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 9, 2018
29. ## Math

We don't need the website. translation 3 units right and 2 units down follows the following rule: (x,y)->(x+3,y-2) 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 9, 2018
30. ## 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 5-5=0, or nothing. 2) if

posted on February 9, 2018
31. ## Math

p+pq = 4(p-pq) p(1+q) = 4p(1-q) Since pq ≠ 0, then we can cancel out p on both sides. => 1+q=4(1-q) Expand and solve for q 1+q=4-4q 5q=4-1=3 q=3/5 Check: (1+q)=1+3/5=8/5 4(1-q)=4(1-3/5)=4(2/5)=8/5 Therefore the value of q is correct and unique.

posted on February 9, 2018
32. ## math

Sorry the sketch did not work out! :(

posted on February 9, 2018
33. ## 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 9, 2018
34. ## 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) = (2-2)/(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
35. ## 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
36. ## 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
37. ## 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
38. ## 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 X-linked alleles, it means that tortoise can only be

posted on January 26, 2018
39. ## 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 21, 2018
40. ## 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
41. ## 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 1, 2017
42. ## 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
43. ## Math

Yes, \$17592.59, to the nearest cent.

posted on September 26, 2017
44. ## 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+C-|B∩C| = 10 A+C-|A∩C| = 14 A+B-|A∩B| = 12 Add three

posted on September 26, 2017
45. ## Math

inflation rate (increase) =(new value-old value)/old value =(82.4-72.6)/72.6 =9.8/72.6 =.134986 =13.4986% =13.50% (to the nearest hundredth of a percent)

posted on September 26, 2017
46. ## 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
47. ## 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) (x-x0)^2+(y-y0)^2+(z-z0)^2=r^2 substituting C(4,-5,0), the equation of the spherical surface is (x-4)^2+(y+5)^2+z^2=10^2=100 Assuming z-coordinate is

posted on September 2, 2017
48. ## Math

The given quadratic equation has no real roots when the determinant is (strictly) negative. This happens when b^2-4*a*c-p36-40=-4 So the condition for f(x)=p has no real roots is when p>-4.

posted on August 17, 2017
49. ## 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
50. ## 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 (1-p)^(n-x) where

posted on August 2, 2017
51. ## Finance

Oh yes, please add machine cost Y(0)=90000 to negative cash-flows. All other calculations remain valid.

posted on August 2, 2017
52. ## 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 cash-flow diagram for three years, using following information

posted on August 2, 2017
53. ## 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(C|D)=13/51. (b) Ace of hearts followed by a black card. P(A∪B)=1/52*26/51=1/102

posted on August 1, 2017
54. ## 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
55. ## 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
56. ## 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 29, 2017
57. ## 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
58. ## 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=-11000-1200/(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
59. ## Math

Approximate the earth as a perfect sphere, with radius 6371 km. Change in longitude = 60-20 = 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
60. ## geometry

Given: D (2,2), E (-2,-1), and F (-3,5). The reflection about the y-axis 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
61. ## 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 13, 2017
62. ## 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 13, 2017
63. ## 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 13, 2017
64. ## 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=(1.117654321-1)/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
65. ## 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 30-C chickens. Count total number of legs 4C+2(30-C) = 86 Simplify and solve for C 4C-2C=86-60 2C=26 C=13 So there are

posted on July 13, 2017
66. ## 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
67. ## 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
68. ## 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
69. ## 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 11, 2017
70. ## 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
71. ## spatial reasoning

I find 8. ||||| =||| |=|| ||=| |||= ==| =|= |==

posted on July 10, 2017
72. ## 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
73. ## 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 right-angle, so there

posted on July 10, 2017
74. ## 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
75. ## 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
76. ## 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
77. ## 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
78. ## 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
79. ## 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 7, 2017
80. ## 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
81. ## b e t Sofia high school (arethametic)

Let the AP be a(n)=a(0)+(n-1)d then we were given a(p)=q => a(0)+(p-1)d=q a(q)=p => a(0)+(q-1)d=p Subtract one equation from the other a(0)-a(0)+(p-1-(q-1))d=q-p simplify (p-q)d=q-p solving, we find that d=-1 substitute d and p in the AP a(p)=a(0)+(p-1)d

posted on July 7, 2017
82. ## 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
83. ## 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)=1-x 0.9x+0.1(1-x)=0.2 isolate x and solve 0.9x-0.1x=0.2-0.1 0.8x=0.1 x=0.125 => 12.5%

posted on July 7, 2017
84. ## 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 6, 2017
85. ## Math

A=biannual payment = 12,000 APR=10% => i=10%/2=0.05 n=number of periods (each six-months) = 10*2=20 Present value P=A*((1+i)^n-1)/(i(1+i)^n) You can substitute values and compute. P is the same as the amount borrowed in a mortgage with a semi-annual

posted on July 6, 2017
86. ## 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 6, 2017
87. ## 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
88. ## 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