Tuesday

April 28, 2015

April 28, 2015

Total # Posts: 33

**math 3**

4/10 chance of rolling 10 3/10 chance of rolling 5 2/10 chance of rolling 25 1/10 chance of rolling 27 Expected value is the sum of the outcomes multiplied by probabilities = (4/10)(10) + (3/10)(5) + (2/10)(25) + (1/10)(27)
*June 11, 2012*

**math 3**

duplicate question
*June 11, 2012*

**math**

sum of first 5 natural numbers = (5)(6)/2 sum of first 21 natural numbers = (21)(22)/2 sum of first 30 natural numbers = 465 = (30)(31)/2 sum of first n natural numbers = (n)(n+1)/2 -- provable by induction
*June 11, 2012*

**math**

C(7,2)*C(8,3) ways of choosing 2 out of 7 men and 3 out of 8 women. C(n,k) = n!/[(k!)(n-k)!] C(15,5) ways of picking 5 committee members out of 15 probability of selecting 2 men and 3 women is good over total -- C(7,2)*C(8,3)/C(15,5)
*June 11, 2012*

**math**

Probability of getting 0 heads is 1/2^6 Probability of getting at least 1 head is the complement -- 1 - 1/2^6
*June 11, 2012*

**math**

Let b be the number of boys, g be the number of girls. "54 pupils in class" b + g = 54 "3 more boys than girls" b = g+3
*June 11, 2012*

**algebra**

87/400
*June 11, 2012*

**Math Algebra**

There are 3 terms, so it is a polynomial. The only variable is x. The highest power of x is x^2 - the degree is 2.
*June 10, 2012*

**math**

The candle has burned up (8hrs)(0.4cm/hr).
*June 10, 2012*

**precalculus/trigonometry**

Intersections with y=x^2 at x=-2 and x=4 describes two points: (-2, y=(-2)^2) and (4, y=4^2) Find the line between those two points.
*June 10, 2012*

**Calc**

Break it into two integrals, integral (sec^2(x)tan(x))dx and integral(-tan(x))dx. Both can be solved using u substitution.
*May 30, 2012*

**pre algebra homework check**

Correct
*May 30, 2012*

**pre algebra check**

Correct
*May 30, 2012*

**pre algebra homework check**

Correct
*May 30, 2012*

**pre algebra**

Does the second roll depend on the outcome of the first roll? (If so, we call the events "dependent". If not, we call them "independent")
*May 30, 2012*

**pre algebra answer check**

Correct
*May 30, 2012*

**pre algebra check**

Correct
*May 30, 2012*

**pre algebra**

The area is A = pi*r^2 We know A = 3.7994ft^2, we know the value for pi. 3.7994ft^2 = pi*r^2 Solve for r.
*May 30, 2012*

**Math**

The cliff makes a right angle with the ocean. The two legs are 50m (the cliff) and 950m (distance on the ocean from the cliff to the ship). Draw the triangle for that, the rest follows.
*May 30, 2012*

**algebra**

Use long division.
*May 30, 2012*

**Algebra 2**

The probability of drawing an even chip is 2/5, and the probability of drawing an odd chip (which does not change due to replacement) is 3/5. (2/5)*(3/5)
*May 30, 2012*

**math**

Assuming fair coins, the probability of obtaining heads on one coin is 0.5. Obtaining two heads has probability 0.5*0.5.
*May 30, 2012*

**math**

There are 7 bronze trophy winners and 7+14+10=31 classmates in total. 7/31
*May 30, 2012*

**Math**

f: T->S is a surjection, so a function g: S->T exists. g takes elements of S to t_i, i in N injectively since f exists. Intuitively g can be rewritten to take elements of S to N. Formally, let h:T->N, with h(t_i) = i. Then h(g): S->N.
*May 30, 2012*

**Precalculus check answers help!**

1), 3) check your algebra 4) I'm not sure where you went wrong on this one. However, sqrt(6)-sqrt(2)/4 is greater than 1 (2.0959 in fact) 2), 5) are correct
*May 30, 2012*

**geometry**

I assume the the only forces on the rocket after launch are due to gravity. Gravity exerts an acceleration of -32ft/s^2. The height function h(t), derived from acceleration a(t) = -32ft/s^2, is h(t) = (1/2)(-32ft/s^2)*t^2 + v_0*t + h_0. v_0 is the initial velocity, and h_0 is ...
*May 30, 2012*

**geometry**

I don't understand the question. You want to find a and b, yet you state their values.
*May 29, 2012*

**3rd grade math**

Calm down, it's not that difficult. Your child is making valuable use of his last week in school. Think back to your mathematics background - I'm sure you understand this sufficiently to explain it. 86/9 -- 9*9 = 81, so 86/9 = 9 remainder 5. Find the largest multiple ...
*May 29, 2012*

**pre algebra**

There are 4 friends - 4 choices for the first friend to be picked up. For every choice of the first picked up, there are 3 friends left - 3 choices for the second friend to be picked up. Following the pattern, 2 choices for the third friend, 1 choice for the fourth. 4*3*2*1 = 24
*May 29, 2012*

**3rd grade math**

Sam has 4 chores to complete - he can choose the order. He has 4 choices for the first chore. For each choice of the first, he can choose 1 of the 3 remaining for the second chore. etc. 4*3*2*1 = 24 This is more generally known as the ordering problem -- there are n! ways to ...
*May 29, 2012*

**pre algebra**

The volume of a cone is given by V = (1/3)*pi*r^2*h. We're given V and h, so solve for r. Remember, the diameter is two times the radius.
*May 29, 2012*

**pre algebra check**

Correct.
*May 29, 2012*

**Geometry**

The 3-dimensional box cannot be described by 2 dimensions.
*May 29, 2012*

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