Thursday
December 18, 2014

Posts by MathMate


Total # Posts: 10,864

math
If the 7-inch hand goes through a complete circle, it would travel the equivalent of the circumference of a circle of radius 7 inches. Use Circumference = 2πr How far would the tip travel from 1 to 4 o'clock?
May 25, 2013

probability
See response to your previous post: http://www.jiskha.com/display.cgi?id=1369507871
May 25, 2013

French
According to the Petit Robert dictionary, it also stands for vélo tout-terrain, which means mountain-bike. So the meaning can differ from one country to another.
May 25, 2013

French
Véhicule tout-terrain
May 25, 2013

Statistics
Here are some numbers for checking your answer. approximately y=2.3x+23 The correlation coefficient is over 0.99.
May 25, 2013

algebra
Reflection about the y-axis is given by: (x,y)-> r(-x,y)
May 25, 2013

Math
It is a binomial distribution, with p=0.6 (probability of success) q=0.4 (probability of failure) n=5 (number of steps) r=2 or 3 (number of successes) P(n,r)=nCr p^r q^(n-r) P(5,2)=5C2 0.6^2 0.4^3 =(5!)/(3!2!) 0.6^2 0.4^3 = 10(0.36)(0.064) = 0.2304 Similarly, for 3 tails, r=3...
May 25, 2013

simple interest and compund interest.
It sounds like you have difficulties putting numbers into the formula you gave me, so I will do the first one for you. You can attempt the second one as a confirmation. A=P(1+rt) Since A=amount, so Amount=P(1+rt) P=3000, so Amount=3000(1+rt) r=0.03 (3%), so Amount=3000(1+0.03t...
May 25, 2013

simple interest and compund interest.
A=amount P=principal=$3000 r=0.03 t=number of years, missing from question. Take out your calculator and calculate according to the formula: A=P(1+rt) Here i=5%=0.05/12 (compounded monthly n=6 years = 6*12=72 months P=principal (unknown) A=final amount = $15000. From A=P(1+i)^...
May 25, 2013

HealthCare Finance Bonds
Sorry, meant "going back to IRS"
May 25, 2013

HealthCare Finance Bonds
a. At 12% yield, with 40% going back to IRA, he nets 12%(1-0.4)=7.2% b. and c dependent on answer of a, will give you a chance to try them.
May 25, 2013

Statistics
Here are a few articles that explain what a p-value is, with examples. One of them is a youtube link, if you so prefer. http://www.stat.ualberta.ca/~hooper/teaching/misc/Pvalue.pdf http://www.youtube.com/channel/HCM26EC2x5oEU http://en.wikipedia.org/wiki/P-value
May 25, 2013

expressions
Since the rate of filling is constant, it is a rule consisting of a linear expression. Let H=height, and x=number of days since today (day 0). Since water rises 2 feet per day, today's height, H = 14 feet. So the rule is then H = 14+2x where 2 = additional depth per day 14...
May 25, 2013

exponents :)
You're welcome!
May 25, 2013

exponents
#4 and #5 are both correct. For #8, it is x^8/y^8, since the question requires positive exponents. (You could have written it as x^8y^-8.) 1. 1/125 is 1/5^3. See if you can find the correct answer. 2. d^4*d^6 is d^10, so correction required. 3. the minus sign before the ...
May 25, 2013

scientific notation am i doing it right?
signature.
May 25, 2013

scientific notation am i doing it right?
Sorry, finger faster than the brain, forgot to change since last post.
May 25, 2013

scientific notation am i doing it right?
#1 is correct. The power of 10 refers to the number of positions the decimal point has to be moved, not the number of zeroes. So for #2, it should be 9.82000*100000=982000 Similarly, for #3, 9x10^3=9/1000=0.009 I will leave #4 for you to try.
May 25, 2013

scientific notation am i doing it right?
All correct, well done!
May 25, 2013

Sequences
Find the rule for number 2, which is a geometric series. You can tell if it is a geometric series by dividing any term by the previous. If the quotient is the same, then it is a geometric series. The rule for a geometric sequence is: t(n)=ar^n and r is the quotient by dividing...
May 25, 2013

Sequences
Let the nth term of the arithmetic sequence be t(n)=ax+b then t(1)=a(1)+b=7 t(2)=a(2)+b=12 Subtracting, we find 2a-a=12-7 which gives a=5 Substitute back into the formula, t(1)=5(1)+b=7, so b=2 the complete rule is then t(n)=5x+2 The nineteenth term is therefore t(19)=5*19+2=...
May 25, 2013

polynomials am i doing it right?
You're on the right track... 1. expand it and write it out when it is a subtraction: (x^4+7x^3+7)-(2x^4-4x^3+1) = x^4+7x^3+7) -2x^4+4x^3-1 = -x^4 + 11 x^3 + 6 2. space out your terms to avoid losing some of them. (3n^3 + n^2 -n -4)+(5n^3 -4n^2 + 11) = 3n^3 + n^2 -n -4 + 5n...
May 25, 2013

How to get quick responses to your math questions
Also, - DO check that the question you are about to post is complete and accurate before pressing the "post" button. - Do not omit parentheses. If the numerator or denominator of a fraction has more than one term, you need parentheses around them when you transcribe ...
May 25, 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 on which branch of ...
May 25, 2013

Physics
Hint: Find the resultant of the two given forces. The third force (which keeps the resultant in equilibrium) is a force which is equal in magnitude to the resultant, but opposite in direction.
May 25, 2013

Maths
Use the property of intersecting chords PA*PB=PC*PD In this case the chords intersect outside of Γ. Also, if T is the tangent to Γ passing through P, then PA*PB=PC*PD=PT²
May 25, 2013

math
Trade discount = $679.95*0.30
May 25, 2013

trig
So on the Cartesian plane, it is in the fourth quadrant, with x-y as (900,-500). Atan(-500/900)= -29° approximately. So the bearing is S61°E.
May 25, 2013

Calculus
Use substitution, p=sin(x), dp=cos(x)dx I=∫ydx =∫cos(x)(2sin(x)-1)^6dx =∫(2p-1)^6 dp Substitute again, u=2p-1, du=2dp I=∫u^6 (dp/2) =u^7/7 ÷2 + C Now back substitute u=2p-1=2sin(x)-1 I=(2sin(x)-1)^7 /14 +C
May 25, 2013

Math/ Algebra
Rewrite the equation in symmetric form x/a + y/b = 1 where a and b are the x- and y-intercepts respectively. y/2 -3x/5 = 1 can be rewritten as: x/(-5/3) + y/2 = 1 Identify the intercepts and graph accordingly.
May 24, 2013

Math
15/20/20 is a successive discount of 15%, followed by 20% on the discounted price, and finally another 20% of the doubly discounted price. For example, $1000 with a trade discount of 15/20/30 would have a final discounted price of $1000*(1-0.15)(1-0.20)(1-0.30)=$476 So the ...
May 24, 2013

Math/ Algebra
See http://www.jiskha.com/display.cgi?id=1369451313
May 24, 2013

Math
p=probability of scoring (success) = 0.8 q=probability of not scoring (failure = 0.2 Assuming the probability does not change over time and is independent of previous results, then we can apply the binomial distribution: P(7+ out of 8) =8C7*0.8^70.2+8C80.8^8 =0.34+.17 =0.50 (...
May 24, 2013

statistics
Ah! I see it now. "y (in tens of thousands of dollars)" That might be the culprit.
May 24, 2013

statistics
Did you put $5.13 or 5.13?
May 24, 2013

Statistics
There are different ways to find the regression line. Do you know which one you are supposed to use? It should be around y=-0.6x+310. Try to calculate the coefficients and we can check you answer. Do specify the method, and work details if you can.
May 24, 2013

statistics
If you are working on the computer, you have to get the answer exactly right. It asked for the answer to 2 decimal places. If you put three (3.625), it could mark you wrong. On the other hand, there are two ways to round it to 2 decimal places. Most people round it up when it ...
May 24, 2013

Math - please help
The height is 280 ft. Distance from apex to mid-point of base = 356.1 ft = slant height. Area of one side = (1/2)base*slant-height then choose the correct answer.
May 24, 2013

Calculus
Let f(x)=sqrt(1+6x) then f'(x)=3/sqrt(6*x+1) and f'(0)=3 Thus the slope of the curve is 3 at x=0. f(0)=1 means that the tangent to the curve passes through (0,1)=(x0,y0). So the linearization is y=Ax+B =Slope(x-x0)+y0 =3(x-0)+1 =3x+1 Identify A and B for your answer.
May 24, 2013

Maths
For x near 1, you can use linearlization, which is f(x)=f'(1)(x-1)+f(1) =(1/8)x+f(1) Therefore, within the errors of the linearization, f(x)-f(1) = (x-1)/8 (approximately)
May 24, 2013

geometry - missing information
To scale or not, we don't get to see it. So we depend on you to describe the figure.
May 24, 2013

please answer simple stat any tutor
Think of the test as μ1>μ2 Is the solution of μ1 on the left, right or both sides of μ2?
May 23, 2013

algebra
slope of line y=(2/5)x+7 is (2/5) Slope of line perpendicular to it is -(1/slope)=-5/2.
May 22, 2013

Frenchhhhhhhhhh
All the cases are direct objects, so you need to replace them by le/la or les (not "des")depending on whether the nouns you are replacing are in singular or plural, and masculine or feminine. There is an extra caution in French is that the pronouns of direct objects ...
May 22, 2013

Frenchhhhhhhhhh
Replace by what?
May 22, 2013

Algebra - clarifications required
y=2x=1 is not an equation of a line. Please clarify the typo.
May 21, 2013

Algebra - clarifications required
1. slope = 15/12 2. slope = -5/4 3. slope = ? (two equal signs, so the sign of the slop could go either way. Please clarify.
May 21, 2013

pre calc
If sin(x)=-3/5 in Q3, then cos(x)=-4/5 (using cos²(x)=1-sin²(x)) Similarly, cos(y)=5/13 in Q1 means sin(y)=12/13 sin(x-y)=sin(x)cos(y)-cos(x)sin(y) =-3/5*5/13 - (-4/5)*12/13 =(-15+48)/65 =33/65
May 21, 2013

Math
Yes, it's correct. 2 gals must be added (and well agitated).
May 21, 2013

Math (Probability)
The size of the sample space of the last throw is 20*20=400. Out of the 400 outcomes, Bret needs those where his throw is 11 or more than Shawn's, namely: (12,1),(13,1),(14,1)...(20,1) (13,2),(14,2)...(20,2) ... (19,8),(20,8) (20,9) There are ∑(i), i=1,9 outcomes. Can ...
May 21, 2013

math
One cup is 240 ml 1 table-spoon is 15 ml. So 1 cup = 16 table-spoons How table-spoons are in 16 gals? This equals how many cups?
May 20, 2013

Math
Certainly, if the father has a foot-length equal to 150% of that of Aaron.
May 20, 2013

Physics
Use the definition of a Coulomb. There are 11 ampères of current 10 minutes = 600 seconds. Can you now figure it out?
May 20, 2013

math
Let E=age of Mr. Edwards. (E+15 + E/3+15) = 86 Solve for E.
May 20, 2013

Pre-Calculus
Draw a right triangle with XY vertical, and a base AX of 200 ft. The angle XAY=25 degrees. Use the definition of tangent(A)=tangent(25°)=XY/AX Solve for XY.
May 20, 2013

7th Grade Math
Volumes are (linear ratio)³ and areas are (linear ratio)²
May 20, 2013

probability
There were 40 outcomes, of which 6 were spinning a 2. Experimental probability = 6/40 = 3/20.
May 20, 2013

7th grade math help :)
You're welcome!
May 20, 2013

7th grade math help
Assuming one must make a single choice in each group, so it is a three-step experiment. choices for group 1 = 2 choices for group 2 = 3 choices for group 3 = 2 Total number of outcomes in the sample space is therefore the product of the choices in each group (step).
May 20, 2013

physics
v0=5.5 m/s v1=0 m/s F=160 N m=80 kg Use Newton's second law, F=ma a=F/m=-2 m/s-2 (deceleration) Use: (v1^2-v0^2)=2aS So S=(v1^2-v0^2)/2a=30.25/4=7.5625 m
May 20, 2013

Physics
F=>M2=>F1=>M1 On the frictionless table, both will have an acceleration a. Draw the free-body-diagrams (FBD) and conclude that M2.a = (F-F1) M1.a = F1 using Newton's second law. Solve for F1 and a. Part (b) can be found in a similar way.
May 20, 2013

calculus
Steve is right. Whenever you transpose a fraction from a book to a single line to post, you need to insert the implicit parentheses. In this case, I believe it is 1000 = 10,000(1 − (5/[5 + e^−0.001x]))
May 20, 2013

calculus
p = 10,000(1 − (5/5 + e^−0.001x)) for p=1000, 1000=10000(1 − (5/5 + e^−0.001x)) 5/(5+e^(-0.001x)=0.9 e^(-0.001x)=5/0.9-5 take log -0.001x = log(5/0.9-5) x=-1000 log(5/0.9-5) =587.8, say 588 (b) can be done in a similar way.
May 20, 2013

Math 208
Let x be the amount he invested at 6%. Then x-1400 is the amount he invested at 5%. Total interest after 1 year x*0.06+(x-1400)*0.05=172 0.11x=172+1400*0.05 0.11x=242 x=2200 Check 2200*0.06+800*0.05=132+40=172 ok.
May 20, 2013

programming - C++ or Java?
The instructions are quite clear as to what to do. I suggest you read through your teacher's notes or instructions and give an attempt. Programming is learned by actually writing and compiling code. Copying or reading alone will not help you solve your next problem. You&#...
May 20, 2013

Physics
Speed of sound in sea water depends on the temperature and salinity. At 25 degrees and 35 ppt salinity, the speed of sound is approximately 1551 m/s. So divide 19000/1551 to give the time in seconds it takes.
May 20, 2013

Math
Basically you cannot. A bar graph puts different numbers into the same class, and so there is loss of information. If you have a problem in hand, post the data (if they are not too numerous) and we can appreciate better the problem in hand.
May 20, 2013

Calculus
Parentheses are implicit when it is printed in fraction form. If it is printed as a fraction, your post is linearizing it (put on a single line) and it is necessary to insert parentheses around all numerators or denominators which contain more than one term.
May 20, 2013

Calculus - clarifications required
Could you please insert parentheses to clarify the question? 10x-3/5x+6x could mean (10x-3)/(5x+6x) [??] 10x -(3/5x) + 6x [??] [(10x-3)/5x] +6x [??} etc.
May 20, 2013

Algebra - clarifications required
Jamila, please clarify what SR stands for. Is it a monetary unit, or is it an abbreviation for some term?
May 20, 2013

calculus
Find derivative with respect to x: y'(x)=dy/dx=6x-5 Evaluate derivative at x=3: y'(3)=6(3)-5=13
May 20, 2013

Algebra
Using calculus, it would be finding dy/dt and equating to zero to solve for t. Since it is algebra, you could complete squares: y=-4.9(t-7)²+49*4.9 =-4.9(t-7)²+240.1 which means that the maximum height of 240.1 m at t=7.
May 20, 2013

math
You can take the average, namely [(1+2)/8]2 = 3/16 If you want just ANY fraction between, you can add the numberators and denominators: (1+1)/(8+4)=2/12 = 1/6
May 20, 2013

Computer Science
Depending on the complexity of the game, it takes proficiency in the language, which means lots of late nights leaning and practising programming on different projects. In short, you have to like it so that it is not work, but fun.
May 20, 2013

please hurry
It is almost impossible to show the calculations here because the proportional font used here makes it difficult to line up calculations. You can look up an example at the following link: http://www.homeschoolmath.net/teaching/square-root-algorithm.php
May 20, 2013

maths-formula
Sorry mate, this expression does not have rational factors.
May 20, 2013

Physics
Since it is an elastic impact, we can equate energies.
May 20, 2013

Probability
Only question left is how Andrew found a fair 10 sided die. Platonic solids have 4,6,8,12 and 20 sides!
May 20, 2013

Probability
Use a probability tree to find that the overall probability of winning is [∑(i²)/100]/10] for i=1 to 10 =385/1000 which should be simplified to an irreduceable fraction a/b. The sum of a+b is then 277.
May 20, 2013

maths
Subdividing a pizza according to the number of people, getting change after paying for a purchase, finding unit price of items in a grocery store to compare unit cost, checking that the restaurant bill is correct, calculating tip, counting money after a withdrawal, finding the...
May 20, 2013

Algebra
See http://www.jiskha.com/display.cgi?id=1369047938
May 19, 2013

Algebra
See http://www.jiskha.com/display.cgi?id=1369047938
May 19, 2013

French-SraJMcGin
Watch spellings of "Sacré-Coeur", as pointed out by Mme Sra. The proper name seems to be "La Basilique du Sacré Coeur"
May 19, 2013

math
This equation is separable, so dy/dx = 6xy dy/y = 6xdx Integrate both sides, log(y)=3x²+C1 y=Ce3x² y(0)=40 -> C=40 therefore y=40e3x²
May 19, 2013

geometry
Draw a rhombus, and mark one side as 24 cm, and one of the diagonals as 24 cm long. Then the half diagonal is 12 cm. Since the diagonals of a rhombus intersect at right angles, we have a right-triangle with hypotenuse 14 cm, with one side as 12. The other half-diagonal is ...
May 19, 2013

Geometry - incomplete?
You are probably missing a diagram or figure. x has not been mentioned in more than one place in the question.
May 19, 2013

advanced algedra 2
Substitute y=x² a) y²-9y+18 =(y-6)(y-3) and put back y=x².
May 19, 2013

Mathematics
θ=133 rpm = 133*2*π/60 radians/s Speed = rθ=40/100 m *θ =1.7733π m/s =5.571 m/s (approx.)
May 19, 2013

math please hurry
Assuming the code uses English alphabet, Choices for first letter: 26 Choices for second letter: 26 Choices for third letter: 26 Choices for digit: 10 Total number of codes = product of all 4 choices.
May 19, 2013

Algebra
Since the title is "algebra", I assume calculus cannot be used. In this case, complete squares of P(x). P=-5(x-20)²+2200 which means that P(x) is at a maximum when x=20, and P(x)=2200.
May 19, 2013

advanced algedra 2
See: http://www.jiskha.com/display.cgi?id=1368991756
May 19, 2013

Geometry
Lateral surface area of a cone Al = πrL r=radius of base L=slant height. So Area of canvas = π(12.5)(26)
May 19, 2013

To GANDU MAN
Your geometry problem of yesterday has been answered. http://www.jiskha.com/display.cgi?id=1368886945
May 19, 2013

math
a^3=1/cos-cos = (1-cos^2)/cos=sin^2/cos b^3=1/sin-sin = (1-sin^2)/sin=cos^2/sin a^3/b^3=sin^2/cos * cos^2/sin=sin^3/cos^3 => a/b=sin/cos = tan (Hope you understand your own notations.)
May 19, 2013

statistics
μ=98.2 σ=0.62 Z(100)=(100-98.2)/0.62=2.903 Look up (normal) probabilities for Z=2.903 from tables (for people with temperatures below 100). Subtract from 1 to get probabilities of healthy person considered having a fever.
May 19, 2013

Mathematics
Assuming radiator reaches 120° between 0 and 4 minutes. Trying to solve: 120 = 6.2t² + 12t +32 or 6.2t² + 12t - 88 = 0 Use quadratic formula to get t=-4.8 or t=2.92 sec. Reject t=-4.8 because it is not within interval [0,4].
May 19, 2013

Algebra
1. The transformations are: e(O,2) : dilation about origin of 2 units t(0,5) : translation 5 units up r(y,-x) : rotation counter-clockwise 90° So (x,y)-> (2x,2y) -> (2x, 2y+5) -> (2y+5, -2x) So combining it all: (x,y) -> (2y+5, -2x) 2. Using Cramer's rule...
May 19, 2013

Physics
We are unable to help you solve the problem without guessing how the objects are configured. You can describe in detail how the objects are arranged, or post the diagram at an external site and post the link.
May 18, 2013

Math 4 questions
"at most" means ≤ "minimuum of" means ≥ "less than" means < "low of" means ≥ "high of" means ≤ You will be more likely to get an answer quickly if you show your attempts.
May 18, 2013

Algebra II Part 2
Thanks Steve, good thought!
May 18, 2013

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