Data Sufficiency

Official Guide

How much did credit-card fraud cost United States banks in year X to the nearest $ 10 million?

1) In year X, counterfeit cards and telephone and mail-order fraud accounted for 39 percent of the total amount that card fraud cost the banks.

2) In year X, stolen cards accounted for $ 158.4 million, or 16 percent, of the total amount that credit-card fraud cost the banks.

OA B

Target question => Find the total amount that credit card costs the banks?

Statement 1 => In year x, counterfeit cards and telephone and mail-order fraud accounted for 39% of the total amount that card fraud cost the banks

This statement only gives a fraction of the total amount of credit card fraud (39%) the remaining 61% is unknown. Statement 1 is NOT SUFFICIENT

Statement 2 => In year x, stolen cards accounted for $158.4 million, or 16%, of the total amount that credit card fraud costs the banks
10% of total credit card fraud = 158.4 million
100% of total credit card fraud = 158.4 * 100 / 16
= 15840/16 = 990 million
Statement 2 alone is sufficient

Answer = B