PSAT Math Multiple-Choice Question 366: Answer and Explanation

Question: 366

Each MRI scan given at a hospital produces about 3.6 gigabits of data. Every night, for 8 hours, the hospital backs up the files of the scans. The hospital computers can upload the MRI scans at a rate of 2 megabits per second. What is the maximum number of MRI scans that the hospital can upload each night? (1 gigabit = 1,024 megabits)

• A. 15
• B. 16
• C. 56
• D. 202

Correct Answer: A

Explanation:

A

Difficulty: Hard

Getting to the Answer: Don't let all the technical words in this question overwhelm you. Solve it step-by-step, examining the units as you go. First, use the factor-label method to determine the number of megabits the computer can upload in one night (8 hours):

Next, convert this amount to gigabits (because the information about the scans is given in gigabits, not megabits):

Finally, each scan produces about 3.6 gigabits of data, so divide this number by 3.6 to determine how many scans the computer can upload to the remote server: scans. You should round this number down to 15, (A), because the computer cannot complete the 16th scan in the time allowed.