Trucks question

I'd be tempted to go for answer D. Can you please post the OA?

thanks

Answer D 8/15n

x is the proportion of trucks
1/4n*x + n*x = n
x = 1 / ( 1/4 + 1 ) = 4/5

numbers of trucks = 4/5*n

2/3 trucks were pickeds up

Answer = 2/3 * 4/5 * n = 8/15*n

Answer D

How to make an educated guess on this one?
Also, the explanation provided below is not really clear to me.

Thanks,

carllecat wrote:How to make an educated guess on this one?
Also, the explanation provided below is not really clear to me.

Thanks,

Folk, in order to answer questions like these quickly you can always assume some numbers.

Since we are dealing with the fractions 1/4 and 2/3, see the the number of trucks that you take is divisible by both 4 and 3 say 12.

So, if number of trucks is 12, number of cars= 1/4(12)=3.
Hence total number of vehicles n = 12+3 =15

Also out of 12 trucks, 2/3 are pickups.
So number of pickups parked in the lot = 2/3(12)=8.

Now from the given choices, substituting n=15, we get 8 for the choice D

sureshbala wrote:

carllecat wrote:How to make an educated guess on this one?
Also, the explanation provided below is not really clear to me.

Thanks,

Folk, in order to answer questions like these quickly you can always assume some numbers.

Since we are dealing with the fractions 1/4 and 2/3, see the the number of trucks that you take is divisible by both 4 and 3 say 12.

So, if number of trucks is 12, number of cars= 1/4(12)=3.
Hence total number of vehicles n = 12+3 =15

Also out of 12 trucks, 2/3 are pickups.
So number of pickups parked in the lot = 2/3(12)=8.

Now from the given choices, substituting n=15, we get 8 for the choice D

Make sense now. Thanks Sureshbala!

One thing to add regarding this question. Be careful when picking numbers b/c the question stem does not say that the total number of cars is 1/4 the number of cars in the lot. It references the truck so be certain to pick smart numbers, unlike me and I ended up with the wrong answer of 1/2N or choice C.

Chosing #s & substituting in the answer choices surely helps, but I felt using variables for this question was much faster.

As per the question, T + C = n ; C = 1/4*T
Substituting C in the original equation gives us T + 1/4*T = n
Hence T = 4n/5

Now, the question is saying that 2/3 of the trucks are pickups, i.e. 2/3*T. Substituting for T, we get 2/3*4n/5 ==> 8n/15

Hope this helps.