An urn contains 4 white and 4 black balls. we randomly choose 4 balls. if 2 of them are white and 2 are black, we stop. if not, we replace the balls in the urn and again randomly select 4 balls. this continues until exactly 2 of the 4 chosen are white. what is the probability that we shall make exactly n selections?

The probability that we shall make exactly n selections is .

Step-by-step explanation:

It is given that an urn contains 4 white and 4 black balls and we randomly choose 4 balls. If 2 of them are white and 2 are black, we stop.

The total number of ways to select exactly 2 white and 2 black balls.

The total number of ways to select 4 balls from 8 balls is

The probability of selecting exactly 2 white and 2 black balls is

The probability of not selecting exactly 2 white and 2 black balls is

If we not get exactly 2 white and 2 black balls, then we replace the balls in the urn and again randomly select 4 balls.

The probability that we shall make exactly n selections is

Therefore the probability that we shall make exactly n selections is .

answer: the answer is (b) amie should have multiplied

step-by-step explanation: given a sphere and a cylinder with same radius and height.

let, 'r' be the radius of the cylinder and sphere and 'h' be the height of the cylinder. according to the question,

r = h.

now, the volume of the sphere will be

and the volume of the cylinder will be

therefore, we have

thus, ammie should have multiplied the volume of the sphere