Friday
November 28, 2014

Posts by MathMate


Total # Posts: 10,830

Physics
Case 1: zero friction F=mg sin(28) a=F/m=g sin(28) S=ut+(1/2)at² 100=0+g sin(28)t²/2 t=sqrt(2*100/(g sin(28)) =6.59 s. Case 2: μk=0.17 Frictional force =μmg cos(28) Net force (assuming μcos<sin) =mg(sin(28)-μcos(28) t=sqrt(2*100/(g (sin(28)-μcos(28...
May 27, 2013

Statistical probability411
If order is not important 14C7=14!/(7!7!) ! means factorial 7!=7×6×5×4×3×2×1 If order is important, which is not explicit in the question, then the answer is 14P7=14!/7!
May 27, 2013

Statistical probability411
14C7=14!/(7!7!) ! means factorial 7!=7×6×5×4×3×2×1
May 27, 2013

math
I think you mean probability is m/n, where m≤n.
May 27, 2013

math
Perimeter=10, therefore sum of two sides =5. Try sides 2 and 3, area=6, so height=222/6=37. Height=37.
May 27, 2013

algebra probability34
No replacement (otherwise two identical poems) Total=4+5+2+2=13 poems 5 Colerdge, 2 Byron So P(CB)=(5/13)*(2/12)
May 26, 2013

algebra probabilty34
14 choose 7 =14C7=14!/(7!7!)
May 26, 2013

math
The closest point (x0,y0) on the circle to point (x1,y1) of the circle is if (x0,y0) lies on the radial line passing through (x1,y1). To show this, first find the centre of the circle x^2+y^2=1 is a circle with radius 1 and centre (0,0). The line through (0,0) and (3,4) is L...
May 26, 2013

Statistics
For mean, you add up all numbers and divide by the size of the population. For median, you need to sort them in increasing order, and take the mean of the two middle numbers (average between 25th and 26th values for N=50). Since the data represent the whole population, they ...
May 26, 2013

statistics- correction
N=10C5=10!/(5!5!)=252
May 26, 2013

statistics
Assume There are N=10C5 ways of randomly choosing 5 horses out of 10. where N=10!/(5!5!)=25 We assume that 1. order does not count, 2. winning probabilities are equal among horses, 3. results are completely random. Then the owner has one chance in 252 that his 5 horses are ...
May 26, 2013

Math :)
You're welcome!
May 26, 2013

Math
April, I see that you have many questions, but have yet to see efforts on your part. I have given a complete solution for this one in the hope that it will help you solve similar problems. If you can show some understanding of the subject matter, such as explaining what ...
May 26, 2013

Math
Net price factor for 25/15/10 is 0.75*0.85*0.9=0.57375. 0.75 comes from 1-25%, 0.85 comes from 1-15% 0.9 comes from 1-10%. The net price is $800*0.57375=$459
May 26, 2013

statistics
Normally distributed data are symmetric about the mean, so 50% goes above and the other 50% goes below the mean.
May 26, 2013

statistics
By definition: P(B|A)=P(B∩A)/P(A) So 0.4=P(B∩A)/0.5 Solve for P(B∩A)
May 26, 2013

statistics
1.0 When data fit exactly onto a straight line, the correlation coefficient is either +1 or -1. If the slope of the line is positive, r=+1. If the slope of the line is negative, r=-1. In this case, the slope=+2, so r=+1.0
May 26, 2013

Math
Zero. g(x) is the tangent to f(x) at x=-3. Show that this is the case by solving for x in the equation f(x)=g(x) and show that it has a double root.
May 26, 2013

French
Conjugaison du verbe "avoir" (to have) au présent indicatif: j'ai tu as il a nous avons vous avez ils ont Since your subject is "je", or I, first person singular, we need to use "ai". "as" is for second person singular. Also, ...
May 26, 2013

math
45-45-90 triangle is isosceles. The other short side is therefore also x. Using Pythagoras theorem, we find hypotenuse²=x²+x²=2x² Solve for hypotenuse.
May 26, 2013

coefficients
A coefficient is the numerical part of each term. 5x^2+3x+66 has coefficients 5, 3, and 66 for the first, second and third terms respectively.
May 26, 2013

Polymonimals!
When you have a negative sign preceding parentheses, do an extra step to remove the parentheses: (m^2-m-4)+(m-5) =m^2-m-4+m-5 =m^2-m+m-4-5 =m^2-9
May 26, 2013

vectors problem!!!! help!!!! :)
You're welcome!
May 26, 2013

vectors problem!!!! help!!!!
This is the magnitude of the cross product. The cross product is obtained by evaluating the determinant p i j k 2 9 0 13 18 0 which is p=0i+0j+(2*18-9*13)k =-81k The magnitude is therefore 81.
May 26, 2013

Statistics
I think you have the right formulas, but the wrong N. N equals 5 (count either number of x values or number of y values). So SSx=197-31²/5=4.8 SSy=39000-440²/5=280 Sxy=2760-31*440/5=32 r=Sxy/sqrt(SSx*SSy)=0.87287
May 26, 2013

Statistics
I was questioning SS(xy) only. We need Sum of xy for calculating other parameters, but not sum of squares of xy. How did you get your answers? I got 197 for SS(x). All of your answers seem to come up a little more than half of mine.
May 26, 2013

Statistics
I do not know if we use the same terminology. Is SS(x) sum of squares of x? If it is, I get 197. Would it be S(xy) instead of SS(xy), meaning just the sum of the products? Does r mean coefficient of correlation, which has a range of -1 to 1. If you get 7.04, perhaps you are ...
May 26, 2013

help!!!!! Probability!!!::)
You're welcome! It would be even better if you would not use various aliases.
May 26, 2013

help!!!!! Probability!!!
Assume die is fair. Rolling twice gives 36 outcomes, of which the second roll is strictly less than the first (successes) can be enumerated as follows: 21,31,32,41,42,43,51,52,53,54,61,62,63,64,65 Count how many successes there are, and divide by the size of the sample space (...
May 26, 2013

math
There is not much to simplify. Is the integration from a to b or from b to a? Your answer is close, but has the wrong sign and missing a term. Remember that e^0 is 1 and not zero.
May 26, 2013

integral calculus
You may want to show your work to know how you got your answer. The good news is that your indefinite integral is correct, but off by 1/24, which can be absorbed in the integration constant. Depending on how you integrated, it could give equivalent results of: (3sin(x)^4-2sin(...
May 26, 2013

Engineering science
Hints: Kinetic energy, KE=(1/2)mv² where m=mass of object (kg) v=velocity (m/s) Potential energy =mgh m=mass in kg g=acceleration due to gravity, m/s-2 h=height above datum in m. To calculate h, you need the distance travelled. For uniform acceleration, distance d, is the...
May 26, 2013

math
The question gives the length of the original log as 50 cm (unless there is a typo). If the two pieces are equal, then each piece would measure 50/2 cm = 25 cm.
May 26, 2013

Statistics
Maple can certainly find r, called the coefficient of correlation. The coefficient of correlation, r, for a population can be calculated using the following formula (one of the different forms): r=(nΣxy-(Σx)( Σy)) / √[(nΣx²-(Σx)²)(...
May 26, 2013

Statistics
Are you expected to use Maple to do this exercise? What are the answers?
May 26, 2013

math
According to the question, 5.13 is in tens of thousand of dollars, so the correct answer should be $51300, and the $ sign is already given before the answer box, right?
May 26, 2013

math
"y (in tens of thousands of dollars)"
May 26, 2013

physics
Acceleration of an object in circular motion is: magnitude = v²/r v = 2 m/s r = 0.5 m Direction is towards the centre of the circle. Mass is irrelevant (unless you need the force on the string).
May 26, 2013

math
Since the fraction of boys who play the games cannot exceed 1, so 4/7+5/8-1 is the fraction who plays both games. 5/8+4/7 - 1 =(35+32-56)/56 =(67-56)/56=11/56
May 26, 2013

French
Bravo, c'est une production écrite créée avec soin! A few little things: - "à Dubai mall" : do you mean a shopping centre? (centre commercial) unless it is a proper name, in which case you would write "Dubai Mall". - "...
May 26, 2013

Math
Let's say we each have two apples. If I give you one apple, you have three and I have one. So the difference is 2 apples. If I give you two apples, you have four and I have none, the difference is 4. We conclude therefore that for every apple I give you, the difference ...
May 26, 2013

Math (Absolute Value Inequality)
You probably would like to find the value of a. We established that to satisfy the quadratic inequality x^2−11x−210 < 0 -10<x<21 Now substitute this interval into each of the two linear inequalities: x-8<a and 8-x <a (-10)-8<a => a>-18 8-(-...
May 26, 2013

Math (Absolute Value Inequality)
If we would like to satisfy the condition: x^2−11x−210 < 0, we need to find the roots of x^2−11x−210=0. By factoring, we have (x-21)(x+10)=0 The leading coefficient (of x^2) is positive, so the curve is concave up. => x<0 between -10 and 21. To...
May 26, 2013

Math/Algebra
The ellipse is centred at the origin (0,0). The standard formula for the ellipse is then x²/a²+y²/b²=1 where 2a=distance between vertices on the major axis =(5-(-5)=10, so a=5 Distance between foci 2c=(4-(-4))=8 so c=4 To find b, we use the relation a²...
May 26, 2013

divide radical
Hint: factorize the numerator: 2b²+2b-6 =2(b²+b-3) which does not have rational factors. You will need to do a division, which is called the Euclidean division (long division), or another method is the synthetic division. It is a little difficult to show the method ...
May 26, 2013

Maths
Line with slope a through a point (x1,y1) has the equation: y=a(x-x1)+y1 Putting a=-2, (x1,y1)=-1,6), we get the line as: y=-2(x-(-1))+6 or y=-2x+4 ....(1) Substitute x=4 in equation 1 to find the value of y, which is the required unknown.
May 26, 2013

Geometry
Without knowing the 8 steps to which you are referring, you can do the following: Factor both numerator and denominator: R(x)=(x-5)(x+6)/[(x-5)(x+4)] You will find the zeroes and asymptotes. Since there is a common factor (x-5), the point f(5) is indeterminate and should be ...
May 25, 2013

MATH315 Elementry Statistics
Some of the requirements of a binomial model are: 1. probability of success is known and does not vary over the experiment 2. Has exactly two outcomes (head/tail, success/failure). 3. has one or multiple steps 4. is a random experiment
May 25, 2013

Math
Not sure if I understood the question. Does it mean that we need to write the formula A=(B+b)h/2 without using parentheses AND without using the multiplication sign? Would it be: A=Bh/2 + bh/2
May 25, 2013

Math
Yes, the calculation is correct for the net price factor.
May 25, 2013

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

math
Hint: a sector is a pie-piece, similar to a slice of pizza. The area of a sector of a given radius is proportional to the central angle. Area of Sector -------------- Area of circle central angle =------------- 360°
May 25, 2013

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

math
Do it just like normal subtraction, except that when you borrow 1 degree, it becomes 60 minutes, ... 41-20-26 23-39-56 -------- 17-40-30
May 25, 2013

PHYSICS
Does it come with a diagram?
May 25, 2013

chemistry
Zn+2HCl -> ZnCl2 + H2 5.5 g of Zn = 5.5/65.382 M =0.0841 M 25 ml of 0.05M HCl = 25/1000*0.05 M = 0.00125 M < 0.0841/2 So the quantity of HCl governs. Assuming all HCl is consumed, amount of Hydrogen = 0.00125/2 M = 0.000625 M Convert that to the required temperature and ...
May 25, 2013

French :)
Je vous en prie!
May 25, 2013

French
Give it a try! You must know the name.
May 25, 2013

French
camping is an English word borrowed by the French language which means 1. the activity of camping 2. camp-ground. "Comment s'appelle" is an expression which translates to "what do you call ...." "ce" => this "terrain de camping"...
May 25, 2013

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

math
If the length of one of its sides is x. Then x/2 is half the side. An altitude divides the equilateral triangle into two congruent right triangles, each with half of one side (x/2) as the short side, the altitude as the long side, and the side (x) as the hypotenuse. So by ...
May 25, 2013

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

math
a' ÷ a = b' ÷ b so a' = b' × a / b
May 25, 2013

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

math
Do you mean sin-1(0.398) = ? ° ? ' ? " = 23.45320822° multiply the decimal part by 60 =23°27.19249' multiply the decimal part by 60 =23°-27'-11.55" (approx.) =23°-27'-12" (nearest second)
May 25, 2013

math
Every 5 minutes, the minutes hand turns 30° If it turns 360° (from 12 to 12), then the distance is 43.96. You can use proportions to find how much distance the tip travels from 1 to 4.
May 25, 2013

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

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