Brandy is trying to decide between two cell phones. one is free with the two-year contract but she will have to pay the sales tax of 8% on the original price of $399 and the monthly charge is $10 more then she currently pays. the other is on sale for $199 plus a percent sales tax. the monthly charge is the same as she currently pays. over the two year contract period which phone will be the lower cost and by how much?

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

40 i don’t know lololol