Rounding off

[ILULA08]

Q37:
If an automobile averaged 22.5 miles per gallon of gasoline, approximately how many kilometers per liter of gasoline did the automobile average? (1 mile = 1.6 kilometers and 1 gallon = 3.8 liters, both rounded to the nearest tenth.)
A. 3.7
B. 9.5
C. 31.4
D. 53.4
E. 136.8

Note: As you can see this problem is very easy but I got confused about this rounding to nearest 10th or 100th. If someone can explain me that, I would really be grateful to him.

Thanks in anticipation

[tohellandback]

22.5 miles per gallon
when you convert the values in kilometers and litres

22.5* 1.6/3.8= 22.5/(something a little more than 2)= something a little less than 11.25
answer B

[sureshsef]

OA is b.

(22.5 x 1.6 )/ 3.8

= 9.5

[enniguy]

Try this problem this way. The moment I looked at 22.5, I multiplied it by 2. I got 45. I multiplied it by another 2 just to get a multiple of 10 on top.

So the question became,

(90/4) * (1.6 / 3.8 )

= (90/4) * (16 / 38)

Canceling 4 and 16,

= 90 * 4 / 38.

Approximately cancel 38 as, 10 times 4. Then you are left with 90 / 10.

Approx. answer is 9 something. 9.5 in this case.

[Scott@TargetTestPrep]

Q37:
If an automobile averaged 22.5 miles per gallon of gasoline, approximately how many kilometers per liter of gasoline did the automobile average? (1 mile = 1.6 kilometers and 1 gallon = 3.8 liters, both rounded to the nearest tenth.)
A. 3.7
B. 9.5
C. 31.4
D. 53.4
E. 136.8

22.5 miles is 22.5 x 1.6 = 36 km.

1 gallon is 3.8 liters.

So the approximate rate, in km/liter, is 36/3.8 = 9.473.

Answer: B