Question

A bakery owner turns on his doughnut machine at $8{:}30$ am. At $11{:}10$ am the machine has completed one third of the day's job. At what time will the doughnut machine complete the job?

$1{:}50$ pm

$3{:}00$ pm

$3{:}30$ pm

$4{:}30$ pm

$5{:}50$ pm

Answer: D

Concepts:date and time ratio and proportion

Difficulty rating: 770

Solution:

From $8{:}30$ am to $11{:}10$ am is $2$ hours and $40$ minutes, or $160$ minutes, to finish one third of the job.

The entire job therefore takes $3 \cdot 160 = 480$ minutes, or $8$ hours.

Eight hours after $8{:}30$ am is $4{:}30$ pm.

Thus, the correct answer is D.

2008 AMC 10A Problem 1

Answer: D

Difficulty rating: 770

Solution:

Problem 1 in Other Years