ps - items

Question

company X produces a items in 4 min and company Y produces b items in 5 min. when they work together for 20 min and produce a certain number of items, which company produces more items ?

1. a > 0,8b
2. company x produces twice as many items as company y

vikramm · Answer

I'm assuming the question means "which company produces more items of that certain number when they work together" 
D I think 
from either 1 or 2 we know Company X's rate is faster than Company Y's.. so X will produce more items than Y when working together.

Else 
E.

FN · Answer

D it is...

1) suff..it just says X makes more products/hour than Y...

2) repeats the same....

gsr · Answer

D fr me too.

In 20 min, A produces 5/a items and B produces 4/b items.
Is 5/a>4/b
A) If a>0.8, it is suff.
B) 5*(a/5) = 2*(b/4); a=2.5b. Suff.

christoph · Answer

i have no OA. imo its B) b/c from 1) we cannot conclude whether a>b...someone told me that he saw a very similar question in real gmat...

ywilfred · Answer

From (1), we can rewrite as 1.25a > b. It means a is smaller than b.Company x makes a/4 items in 1 minute, and Company Y makes b/5 items in 1 minute. Since b is larger than a, then in the 20 min period, Company Y makes more items. Statement (1) is sufficient.

From (2), we do not have important information as all we know is company x produces 2 times as many items company y at the end of the day. We do not have any other useful information to deduce a and b.

Ans: A

christoph · Answer

1) is insuff b/c x produces a/4 and y b/5 items per min. 1) states a>0,8b = a/4>(0,8b)/5 => a>16/25b => b=25 a can be 17 18 19 20...hence a is faster or slower

kfranson · Answer

That's the catch, you are NOT trying to conclude whether a>b, you are trying to conclude whose RATE is greater which means you need to know a/time and b/time. Since they gave a time relationship for a and b in the problem (x does a in 4 minutes, y does b in 5 minutes) and they give you a relationship for a and b themselves in statement 1) you can solve the problem. So long as a is greater 0.8b, the RATE of x will be higher. Statement one tells you that a is less than b by 80% so set b = 10, then a > 8. So the rate for y is 10/5 = 2 things/minute, the rate for x is > 8/4 which means the rate for x is > 2 things/minute.

You were correct in saying that you cannot conclude a > b b/c in the example I used above where b = 10, a could have been 9, 10, 11 or anything greater than 0.8*10. The key is that the RATE for x is still higher when a = 9, 10, 11...etc...

rigger · Answer

(1) It is insufficient. From this we get the following a/4 > b/5. No where in this statement is rate discussed. Therefore we cannot assume we are talking about rates. We must treat these as numbers.

Here is an example: Let a = 4.1 and b = 5. The inequality a/4 > b/5 is still true. However, a < b. 

Here is another example: Let a = 6 and b = 5. The inequality a/b > b/5 is still true. However, b > a

Therefore (1) is insufficient.

(2) In 20 minutes, the company X produces twice as much as company Y. Since the rate to amount of product produced is directly proportional (since time is constant), this statement should be sufficient.


Therefore I pick  B .

rigger · Answer

Actually, I decide that  E  is the best answer. 

(2) is not sufficient.

kfranson · Answer

Rate is mentioned in the first line of the problem, x can produce a items in 4 minutes (items/time is rate) and y can produce b items in 5 minutes (items/time is rate). If you have a relationship for a and b you can now determine whose rate (items/time) is higher and if two machines operate for the same amount of time then the one with the higher rate will produce more items. Statement one provides the relationship we need between a and b.

dil66 · Answer

Just thought of pointing out that 1.25a > b does not prove a is smaller than b. For example, if a = 4, b =3
1.25 a = 5 > 3 and a > b.

HongHu · Answer

The 20 minutes working together is extra information to throw us off. What we really want to know is that if they work for the same hours who produces more, in other words, who produces faster?

We know X produces a per 4 min, or a/4 per minute. Y produces b per 5 min, or b/5 per minute. So we just need to compare these two numbers.

1. a>0.8b
a/4>0.8b/4=b/5
So X is faster. Sufficient.

2. This is a little ambiguous. Does X produce twice as many items as Y in different time? Considering the last sentence in the question stem, however, I would interpret this sentence to mean that during that 20 minutes X produces twice as Y does. In other words it directly answered the question. A bit strange, but it is sufficient.

So I'd choose D.

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