An Experienced Accountant Can Balance the Books Twice as Fast $16 \mathrm{hr}$

Multiple Choice

An experienced accountant can balance the books twice as fast as a new accountant. Working together it takes the accountants 8 hours. How long would it take the experienced accountant working alone?

A) $16 \mathrm{hr}$
B) $4 \mathrm{hr}$
C) $20 \mathrm{hr}$
D) $12 \mathrm{hr}$