A box contains 35 gems, of which 10 are real diamonds and 25 are fake diamonds. Gems are randomly taken out of the box, one at a time without replacement. What is the probability that exactly 2 fakes are selected?

Step-by-step explanation:

Given

Required

Determine the probability of selecting two fakes

The probability can be represented as thus:

Using the following probability formula, we have:

Each probability is calculated by dividing number of fakes by total number of gems:

The minus 1 (-1) represent the numbers of fake and total gems left after the first selection

Hence, the required probability is approximately 0.504

answer: l

step-by-step explanation:

see explanation

step-by-step explanation:

since the sequence is geometric there is a common ratio r between consecutive terms, that is

r = 4 ÷ - 2 = - 2

r = - 8 ÷ 4 = - 2

r = 16 ÷ 8 = - 2

the next term - 13 must be incorrect as it should be - 32 for the sequence to be geometric.

the first 4 terms are therefore geometric with common ratio r = - 2