Friday

January 20, 2017
Total # Posts: 764

**math**

It depends on the distribution of x bar.

*February 20, 2016*

**math**

6 topping choices, 2 toppings per pizza: 6 choose 2, which is 6!/(2!4!)

*February 20, 2016*

**Stats/Probability**

"Red OR Yellow" should be a giveaway. Here P(A and B)=0 because a red car is not yellow. P(A)+P(B)=0.12+0.04 = 0.16

*February 20, 2016*

**computer science**

4×512MB = 2GB = 2^31 bytes. To address any byte requires 31 bits.

*February 20, 2016*

**theoretical probability**

There are 2 digits (8,9) greater than 7. So every student has a 1/5 chance of choosing a digit greater than 7. With 25 students, the expected number that choose a digit greater than 7 is 25/5 = 5. I would not say the "predicted" number, but rather the "expected&...

*February 20, 2016*

**math**

b) He can throw 5 types of pitches each pitch. With 5 pitches, there are 5^5 possible combinations.

*May 20, 2011*

**algebra**

When the world record is less than 3.1, R is less than 3.1. 3.1 = -0.075t + 3.85 Solve for t (in years after 1930).

*May 20, 2011*

**computer science**

File sizes are given in bytes, while download speeds are given in bits. 4 GB = 4*1024 MB = 4*1024^2 KB = 4*1024^3 Bytes - 4*1024^3*8 bits. 43.2kbps = 43.2*1000 bits per second. The time required is 795.364s, or 220.935 hours. Note that 43.2kbps is quite a low bandwidth.

*May 20, 2011*

**Math**

The fence forms the perimeter of the rectangle. What is the perimeter?

*May 19, 2011*

**geometry**

It doesn't. 100 is not divisible by 6, nor is 83 divisible by 5.

*May 14, 2011*

**Math**

13 is a good guess. But when in 2011 do they actually turn 13?

*May 14, 2011*

**math**

What is the equation for the volume of a sphere? Try googling it.

*May 14, 2011*

**math**

How many inches are in a foot?

*May 14, 2011*

**Trig- Check my answer Please**

What is the length of <-1,-2>? Divide <-1,-2> by its length, giving the result a length of 1 - an unit vector.

*May 14, 2011*

**math**

How could you get only x on the left hand side?

*May 14, 2011*

**math**

Is the domain of g equal to A? Is the range of g a subset of B? if both are true, then g maps A to B.

*May 14, 2011*

**math geometry**

Use Pythagorean Theorem. a^2 + b^2 = c^2, where c is the hypotenuse of the right triangle.

*February 14, 2011*

**Math**

Find the slope and y intercept of each, and compare. m = (y1-y2)/(x1-x2) to find the slope. y - y1 = m(x-x1) to write the line in slope-intercept form.

*February 9, 2011*

**Algebra**

You can factor out a 4a from each term.

*February 3, 2011*

**Math Algebra 2**

Substitute in the values of p and r. p = 10 r = -4 p^2 - r^2 = (10)^2 - (-4)^2 = ?

*January 27, 2011*

**MATH**

No two numbers add to 50. Therefore we must use at least 3 numbers to get the sum. 25+19+6 = 50: a solution exists for 3 numbers.

*January 27, 2011*

**math**

(1/8)-(1/8)2+(1/8)3 = (1/8)(1-2+3) by factoring.

*January 25, 2011*

**beginning algebra**

2 + 7/y = 3/5 7/y = 3/5 - 2 y/7 = 1/(3/5 - 2)

*January 22, 2011*

**College Algebra**

Correct

*January 22, 2011*

**algebra**

The probability that Jonas gets an orange is 5/11. Given that Jonas gets an orange, the probability that Beth gets an apple is 4/10. So the probability that Jonas gets an orange and Beth gets an apple is (5/11)*(4/10).

*January 20, 2011*

**algebra**

y - y1 = m(x - x1) The point (x1, y1) is given as (4, -5). The slope m is given as -3.

*January 20, 2011*

**MATH**

881/5 = 880/5 + 1/5

*January 18, 2011*

**Geometry**

Let x and y be the sides. By Pythagorean Theorem, x^2 + y^2 = 600^2. x+y+600 = 1400

*January 18, 2011*

**Math**

Elaine takes 2.8s more than Pamela: Elaine takes 2.8s + 52.3s =

*January 18, 2011*

**Math**

To find the inverse, swap f(x) and x: f(x) = 10x-5 x = 10f^-1(x)-5 Now solve for f^-1(x).

*January 18, 2011*

**Math**

Set up a proportion: 8%/56 = 100%/x

*January 15, 2011*

**Algebra**

x^2-6x-3=0 x = (-b +/- sqrt(b^2-4ac))/(2a) x = (6 +/- sqrt(6^2 - 4(1)(-3)) ) / (2(1))

*January 15, 2011*

**algebra**

Plug the values in. h = 50m t = 2s v = 30m/s h+vt+4.9*t^2=?

*January 15, 2011*

**math**

The difference of two squares is a^2-b^2, for a and b any expression. It should be easy to determine if a polynomial fits that form.

*January 15, 2011*

**physics**

V=d/t d=V*t Let t be the time the man is jogging. t-2 is the time the dog is running (since the dog waits 2s). When they catch up with each other displacement will be equal. (4m/s)(t-2)=(1.8m/s)(t)

*January 15, 2011*

**Preap Physics!!**

There are several types of potential energy - spring potential energy, chemical potential energy, etc.

*January 11, 2011*

**math**

If the relationship is linear, then the line formed by any two points will pass through all points. Find the line through the first two points. Then check to see if the rest of the points are on that line.

*January 11, 2011*

**algebra**

There are two solutions because of the absolute value sign. x-3x+5 = 7 or x-3x+5 = -7

*January 11, 2011*

**algebra 2**

yes

*January 10, 2011*

**algebra 2**

You can factor out 4x from both terms.

*January 10, 2011*

**algebra**

Jeffs car takes 20% less gas, so it gets 21/(1-0.2) miles per gallon. To drive 570 miles at 21 miles per gallon requires 570/21 gallons.

*January 10, 2011*

**math**

Teaching makes you learn something well. You've had scientific notation in class, right? Pretend I don't know scientific notation, and explain to me what it is. (That will be your answer).

*January 10, 2011*

**Algebra**

Let x be the amount of time of the breakeven point. Then 84+50x = 60x.

*January 9, 2011*

**Algebra 2**

Use synthetic division with -3, then factor the remainder.

*January 9, 2011*

**algebra**

f(x) = 2x^2-3x f(0) = 2(0)^2-3(0) = 0 f(-1) = 2(-1)^2-3(-1) f(2)=?

*January 9, 2011*

**math**

Let a be the value of "a", e be the value of "e", etc. for i, o, and u. Audacious has a u a i o u = 260. So 2a+i+o+2u = 260. Do the same for the other 4 words; you have 5 equations for 5 variables.

*January 9, 2011*

**algebra 2**

The zeroes are 1, 2, and 3, so the factors are (x-1), (x-2), and (x-3). Those are 3 factors for a 3rd degree polynomial, so no other factors are needed. f(x) = C*(x-1)(x-2)(x-3), where C is any constant. f(0) = 18 allows you to determine C.

*January 9, 2011*

**probability**

There are 15 choose 4 ways to choose 4 toppings. There are 15 choose 2 ways to choose salami, green pepper, and 2 other toppings. P{salami and green pepper) = C(15, 2) / C(15,4).

*January 9, 2011*

**Math: Algebra 2**

Try factoring out (2x-3) through grouping.

*January 9, 2011*

**Math**

Suppose you buy x shirts to be shipped as one order. What is the cost of the shirts? What is the cost of shipping?

*January 9, 2011*

**geometry**

The diagonal forms a right triangle with 2 sides of the square. The sides are of equal length, so you can use Pythagorean Theorem to find a side of the square.

*January 9, 2011*

**Algebra**

What variables did you use in part a?

*January 9, 2011*

**Algebra II**

x^2+2x-3 factors into (x+3)(x-1). You can divide x^4-5x^3-16x^2+23x-3 by (x+3) and (x-1) using synthetic division, which may be easier.

*January 9, 2011*

**math analysis**

If csc(x) = 30/150, sin(x) = 150/30. That is not in the range of sine.

*January 9, 2011*

**Math**

Try writing an equation for each problem. It's easy to make a mistake while glancing over the answer choices.

*January 9, 2011*

**Calculus**

The derivative of ln(u) is u'/u. Use Chain Rule for the rest.

*January 9, 2011*

**math**

The points at the tail of the skew affect the mean, but the median will remain in the middle of the curve.

*January 9, 2011*

**algebra**

-2x-<-2x-1 -< is not defined.

*January 7, 2011*

**Math**

Use L'hopital's Rule.

*January 7, 2011*

**math**

a > b = "a is greater than b" a < b = "a is less than b"

*January 6, 2011*

**algebra**

What is your question?

*January 6, 2011*

**physics**

q1 exerts a force on q in the positive direction, and q2 exerts a force on q in the negative direction. F = k(q1q2)/r^2 is the force exerted on one point charge by another. ΣF = k(q*q1)/(0.24)^2 - k(q*q2)/(0.37)^2 = 24. q and q1 are given. q2=?

*January 6, 2011*

**Math**

The player makes 60% of the shots. So the odds are 60:40 in favor of her making the first shot.

*January 6, 2011*

**Physics-Please check**

1) Yes, the gravitational force diminishes the farther you get, but by what factor? Check the equation. 2) The speed of the earth keeps it in orbit around the sun. Changing the mass changes the gravitational force, which is also the centripetal force for the orbit.

*January 5, 2011*

**Math**

Yes

*January 5, 2011*

**algebra**

What is your question?

*January 5, 2011*

**math**

You gain $3 if you get a 6, and always pay $0.90. E[X] = (1/6)*3 - $0.90

*January 5, 2011*

**math**

Pythagorean Theorem: a^2 + b^2 = c^2 c is the hypotenuse

*January 5, 2011*

**algebra**

25% was marked off the original price of $88.

*January 4, 2011*

**fraction x whole number**

7/10*30 = 7/10*10*3 = 7*3 = 21

*January 4, 2011*

**algebra**

If |3n+5| = 7, then 3n+5 = 7 or 3n+5 = -7. There are two possibilities for n; find both.

*January 4, 2011*

**Math**

18 < 20-w 18-20 < 20-w-20 -2 < -w Flip the inequality sign when multiplying by -1. 2 > w

*January 4, 2011*

**science**

The boiling point and condensation point are identical.

*January 4, 2011*

**Math**

Yes

*January 4, 2011*

**Math pre-algebra**

3/1.65 = 5/x

*January 4, 2011*

**math**

Let x be the amount of money Beth has. Let y be the amount of money Suzy has. "beth has $0.60 more than suzy." x = 0.60+y. "together they have $8.20." x+y = 8.20 Solve the system of equations.

*January 4, 2011*

**Math**

<-- -10 ... -7 -6 ... 0 1 2 ... --> Numbers are ascending left to right. Is -7 to the left or to the right of -6?

*January 4, 2011*

**Math**

Draw a number line, and label -7 and -6.

*January 4, 2011*

**Math**

x+8 < 11 x+8-8 < 11-8 x < 3 Inequalities are almost like regular equations.

*January 4, 2011*

**Math**

x+8<11 implies x<3. What is your question?

*January 4, 2011*

**Pre-Algebra**

12+5 > y-5+5 17 > y

*January 4, 2011*

**math**

Ok. Then the perimeter of the triangle is w + l/2 + 5. So w+l/2+5 = 12m, and 2(l+w)=22m.

*January 4, 2011*

**math**

Is the base of the triangle the width of the rectangle, and the height of the triangle half the length of the rectangle?

*January 4, 2011*

**math**

Are you referring to the triangle formed by the diagonal of the rectangle and two of its sides? If the dimensions are 8m by 3m, the hypotenuse of said triangle cannot be 5m.

*January 4, 2011*

**math**

The perimeter of the rectangle is 22m. So 2(l+w) = 22. l+w = 11 l = 11-w Also, l^2+w^2 = 5^2 by Pythagorean Theorem. Substitute in l = 11-w: (11-w)^2+w^2=5^2

*January 4, 2011*

**math**

Let l be the length, and w be the width, of the rectangle. The perimeter of the rectangle is 2(l+w). The perimeter of the triangle is l+w+sqrt(l^2+w^2). sqrt(l^2+w^2) is the hypotenuse of the triangle. There are two equations and two variables. Find l and w.

*January 4, 2011*

**math**

(2/5)Q <= -18 Q <= (-18)/(2/5)

*January 4, 2011*

**Math**

2+m < 2 2+m-2 < 2-2 m < 0

*January 4, 2011*

**Math**

I appreciate trying to help, but please work out the problems to show how the answer is reached. (It also helps to check your work). Standard form of a line is ax+by = c, with a, b, and c integers. y+2 = (1/2)(x-4) Distribute the (1/2). y+2 = x/2-2 Multiply by 2 to make the ...

*January 4, 2011*

**Math**

Factoring the tens is a technique for mental multiplication which relies on the fact that 10*n, for any real number n, is easy to compute. 6*2 = 12 is a memory value. 6*20 = 6*2*10 = 12*10 = 120 60*20 = 6*10*2*10 = 12*10*10 = 1200

*January 4, 2011*

**algebra**

Substitute in x = 35-5y in 4x+9y = 52. 4(35-5y)+9y = 52 Solve for y. Then, plug the value of y into either of the original equations to find x.

*January 4, 2011*

**algebra**

6.67*10^-11 = 6.67/10^11

*January 4, 2011*

**Math**

10-4(5x+1) Distribute the 4 =10-20x-4 =6-20x

*January 4, 2011*

**Math**

This is a simple triangle problem - it may help to draw it out. Draw the height perpendicular to the ground, and the ramp is the hypotenuse. The solution is a proportion. Let x be Pam's height. Then 15/9 = (15+20)/x. x=?

*January 4, 2011*

**Math/Trig**

The period of the parent function is 2pi. The factor of 1/2 applied to x changes the period to 2pi/(1/2) = 4pi.

*January 4, 2011*

**Math**

t is the price of the movie ticket. We know that 3 tickets is less than twenty dollars, because the student got change back. 3t < 20

*January 3, 2011*

**math**

That is an expression. What is your question?

*January 3, 2011*

**math**

8*5*9 = 4*2*5*9 = 4*10*9 = 36*10 = 360

*January 3, 2011*

**algebra**

Given the slope m and the point (x1, y1), use the equation y-y1 = m(x-x1) to find the equation of the line.

*January 3, 2011*

**algebra**

At any value of x on the horizontal line, y is still 2. Therefore, y=2 is the equation of the horizontal line. Similarly, x is always 3 on the vertical line. So x=3 is the vertical line.

*January 3, 2011*