Question

Describe the error in the work shown.

A small submarine starts at –1,260 feet in relation to sea level. Then it descends 5 feet per minute for 12 minutes. What is the new position of the submarine in relation to sea level?


It Has To be right


–1,260 + (–5)(12) = –1,260 + 60

= –1,200

Answer 1

(-5)(12) is equal to -60 not 60

Answer 2

The error is that instead of subtracting 60 feet from -1260, the expression adds this quantity.

Explanation:

If starting at -1260 feet, and then going down (descending) 60 feet (result of descending 5 feet every minute for 12 minutes), the correct operation is:

-1260 + (-5)(12)= -1260-60= -1320