Please double check me

Question

Brent washes 6 cars in 72minutes. How many minutes does it take Brent to wash one car
a. 6 min
b 12min
c 18 min
d 24 min
Answet: b
Approxiamtely 4 out of 10 Students at Marc's college live on campus. The college has 3,000 students. How many of them live on campus?
a. 600
b 1800
c 1500
d 1200
answer: d
The electricity costs of a business decreased from 11,000 one year to 10,000 the next. To the nearest whole percent, what was the rate of decrease?
a 7%
b 18%
c 9%
d 10%
answwer: b
8,000lb = tons
a 3
b 4
c 5
d 6
answer: b

Answer 1

Three of the four answers are correct. :-)

The third answer is wrong.

$11,000 / 1,000 = 0.091 = 9%

Answer 2

$1,000 / $11,000 = 0.091 = 9%

Answer 3

Ms. Sue
Are my other question correct?

Answer 4

Yes. Your other questions are correct.

Answer 5

Thank You

Answer 6

You're welcome. :-)