# Thread: [SOLVED] Probability of independent selections

1. ## [SOLVED] Probability of independent selections

A gasoline tank for a certain car is designed to hold 15 gal of gas. Suppose that the variable x = actual capacity of a randomly selected tank has a distribution that is well approximated by a normal curve with mean 15.0 gal and standard deviation 0.1 gal.

c) If two such tanks are independently selected, what is the probability that both hold at most 15 gal?

Okay, I don't really understand this question. Do I need the info from the first two questions? If so, here is what they are:

a) What is the probability that a randomly selected tank will hold at most 14.8 gal?
b) What is the probability that a randomly selected tank will hold between 14.7 and 15.1 gal?

Or are those two questions separate from the third? I vaguely remember doing this last year but I'm lost. I did the first two so no worries about them but the third has me hung up.

2. Originally Posted by Ghostgirl
A gasoline tank for a certain car is designed to hold 15 gal of gas. Suppose that the variable x = actual capacity of a randomly selected tank has a distribution that is well approximated by a normal curve with mean 15.0 gal and standard deviation 0.1 gal.

c) If two such tanks are independently selected, what is the probability that both hold at most 15 gal?

Okay, I don't really understand this question. Do I need the info from the first two questions? If so, here is what they are:

a) What is the probability that a randomly selected tank will hold at most 14.8 gal?
b) What is the probability that a randomly selected tank will hold between 14.7 and 15.1 gal?

Or are those two questions separate from the third? I vaguely remember doing this last year but I'm lost. I did the first two so no worries about them but the third has me hung up.
Let X be the random variable 'capacity of a tank'. Calculate $p = Pr(X < 15)$. Then the answer to (c) is p^2.