Acell phone company found that 15 of their phones sold in june were defective. the company sold 250 phones in june. how many of the 300 phones sold in july should they expect to be defective? the ratio of sophomores to juniors in the chess club is 3: 5. there are 12 sophomores in the chess club. how many juniors are there?

For every 3 sophmores there are 5 juniors. If there are 12 sophmores then there must me 20 juniors because (3*4)=12, therefore (5*4)=20.

This ratio can also be looked as a fraction.

3/5 which is the same as 12/20

85.560%

step-by-step explanation:

conditional probability is defined as:

p(a|b) = p(a∩b) / p(b)

in other words, the probability that a occurs, given that b has occurred = the probability that both a and b occur / the probability that b occurs.

in this example:

p(turns 64 | turns 44) = p(turns 64 & turns 44) / p(turns 44).

if someone turns 64, they must have already turned 44, so:

p(turns 64 | turns 44) = p(turns 64) / p(turns 44)

on page 42, we see that of the original 100,000, 94944 turn 44, and 81234 turn 64.   therefore:

p(turns 64 | turns 44) = 81234 / 94944

p(turns 64 | turns 44) = 0.85560