Osira wrote:

Question:Out of 5.5 billion of bacteria grown for an experiment, 1 in 75 million has a particular mutation. Approximately how many of these bacteria have the mutation?

(a) 7

(b) 73

(c) 733

(d) 7,333

(e) 73,333

One good way to keep track of large numbers (especially those that won't fit in the GRE calculator!) is to use scientific notation (or a loose version thereof --- for instance, if 5.5 billion in scientific notation is 5.5 x 10 to the 9th (but it would be equally correct for your purposes to write it as 55 x 10 to the 6th)

5.5 billion = 5,500,000,000 = 5.5 x 10 to the 9th

75 million = 75,000,000 = 75 x 10 to the 6th

Since 1 in 75 mil;of the bacteria have the mutation, divide 5.5 billion by 75 million

answer is (e)

the ans should be B, NOT E, check it out, thanks.