At a speed of 50 miles per hour, a certain car uses 1 gallon of gasoline every 30 miles. If the car starts with a full 12 gallon tank of gasoline and travels for 5 hours @ 50 miles per hour, the amount of gasoline used would be what fraction of a full tank?
A. 3/25
B. 11/36
C. 7/12
D. 2/3
E. 25/36
Please explain...thanks.
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nimish_rulz
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Ok here we go---
The total distance traveled by the car in 5hrs = Speed *time= 50*5=250
now 250 miles is the total distance
Since the car uses 1 gallon for every 30 KMs
for 250 miles it will use
250/30 = 25/3 gallons
now the total fraction of original is (25/3)/12 = 25/36.
The total distance traveled by the car in 5hrs = Speed *time= 50*5=250
now 250 miles is the total distance
Since the car uses 1 gallon for every 30 KMs
for 250 miles it will use
250/30 = 25/3 gallons
now the total fraction of original is (25/3)/12 = 25/36.
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lunarpower
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yeah.
make sure that you get good at division with fractions. in this problem, you have to divide 25/3 by 12. there are two ways to go about doing this:
(1) slow, but acceptable if you can do it quickly
write 12 as 12/1. then follow the reciprocal rule, whereby division by a fraction becomes multiplication by its reciprocal:
(25/3) x (1/12) = 25/36
(2) faster
just think about what division means: if you divide something by 12, then obviously it has to get smaller.
there are only two places you could put the '12' here: in the numerator or in the denominator. if it goes into the numerator, it makes the number bigger, which is bad; if it goes into the denominator, it makes the number smaller, which is good. therefore, the '12' gets multiplied into the denominator.
make sure that you get good at division with fractions. in this problem, you have to divide 25/3 by 12. there are two ways to go about doing this:
(1) slow, but acceptable if you can do it quickly
write 12 as 12/1. then follow the reciprocal rule, whereby division by a fraction becomes multiplication by its reciprocal:
(25/3) x (1/12) = 25/36
(2) faster
just think about what division means: if you divide something by 12, then obviously it has to get smaller.
there are only two places you could put the '12' here: in the numerator or in the denominator. if it goes into the numerator, it makes the number bigger, which is bad; if it goes into the denominator, it makes the number smaller, which is good. therefore, the '12' gets multiplied into the denominator.
Ron has been teaching various standardized tests for 20 years.
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Pueden hacerle preguntas a Ron en castellano
Potete chiedere domande a Ron in italiano
On peut poser des questions à Ron en français
Voit esittää kysymyksiä Ron:lle myös suomeksi
--
Quand on se sent bien dans un vêtement, tout peut arriver. Un bon vêtement, c'est un passeport pour le bonheur.
Yves Saint-Laurent
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Learn more about ron
