Before the regime change, the National Museum regularly...

[BTGmoderatorLU]

Before the regime change, the National Museum regularly displayed only one third of the artifacts in its collection; the other two thirds were kept in storage. The National Museum's curator estimates that one seventh to one fifth of the artifacts in the museum's collection disappeared during the regime change. If the National Museum now wishes to display the same number of artifacts as it did before the regime change, and if none of the missing artifacts are recovered, then the museum will keep in storage:

A) 4/5 to 6/7 of artifacts in collection.
B) 9/14 to 13/20
C) 3/5 to 5/7
D) 7/12 to 11/18
E) 7/18 to 5/12

The OA is D.

I'm really confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.

[EconomistGMATTutor]

Hello LUANDATO.

Let's take a look at your question.

Let's suppose that the museum had 105 artifacts. So, before of the regime change, the museum showed 105/3 = 35 artifacts, and the other 70 artifacts where kept in storage.

It says that between 1/7 and 1/5 of the artifacts disappeared, that is to say, between 105/7 = 15 and 105/5 = 21.

So, in storage, there are between 105-21 = 84 and 105-15 = 90 artifacts right now.

If the museum wants to show the same number of artifacts as it did before the regime change, then it wants to show 35 artifacts. Therefore, they will kept in storage between 84-35= 49 and 90-35 = 55 artifacts.

It implies that they will keep in storage between $$49=\frac{7}{12}\cdot84\ \ \ \ and\ \ \ \ \ 55\ =\ \frac{11}{18}\cdot90\ artifacts.$$ So, the correct answer is D.

I hope this explanation may help you.

I'm available if you'd like a follow-up.

Regards.

[Scott@TargetTestPrep]

Before the regime change, the National Museum regularly displayed only one third of the artifacts in its collection; the other two thirds were kept in storage. The National Museum's curator estimates that one seventh to one fifth of the artifacts in the museum's collection disappeared during the regime change. If the National Museum now wishes to display the same number of artifacts as it did before the regime change, and if none of the missing artifacts are recovered, then the museum will keep in storage:

A) 4/5 to 6/7 of artifacts in collection.
B) 9/14 to 13/20
C) 3/5 to 5/7
D) 7/12 to 11/18
E) 7/18 to 5/12

The OA is D.

I'm really confused with this PS question. Please, can any expert assist me with it? Thanks in advanced.

We can let the original number of artifacts = 420.

Thus, 140 were displayed, and 280 were not.

We also see that between 1/7 x 420 = 60 and 1/5 x 420 = 84 disappeared during the regime change.

So there is now a total between 336 and 360 left.

If 140 artifacts are to be displayed, just like before the regime change, the number in storage will be between 336 - 140 = 196 and 360 - 140 = 220.

Thus, 196/336 = 7/12 to 220/360 = 11/18 will remain in storage. Notice that calculating only one of these values allows us to eliminate all other answer choices.

Answer: D