Please provide a detailed solution for this problem

[Architj]

At a certain stock exchange, the opening price of 3780 different stocks which were listed, were all different on two consecutive days. The number of stocks which opened at a lower price on the second day than on the first day was 9(1/11)% lesser than the number that opened at a higher price. How many of stocks opened at a higher price on the second day than on the first day?

a. 2160
b. 1980
c. 1800
d. 1260
e. 940

[GMATGuruNY]

This problem is virtually identical to PS71 in the OG13.

At a certain stock exchange, the opening price of 3780 different stocks which were listed, were all different on two consecutive days. The number of stocks which opened at a lower price on the second day than on the first day was 9(1/11)% lesser than the number that opened at a higher price. How many of stocks opened at a higher price on the second day than on the first day?

a. 2160
b. 1980
c. 1800
d. 1260
e. 940

We can PLUG IN THE ANSWERS, which represent the number of stocks that opened at a higher price.
Since the number of stocks that opened at a higher price is GREATER than the number of stocks that opened at a lower price, more than HALF of the 3780 stocks must have opened at a higher price.
Since 3780/2 = 1890, the correct answer choice must be greater than 1890.
Eliminate C, D and E.

The number of stocks which opened at a lower price on the second day was 9(1/11)% lesser than the number that opened at a higher price.
Since (9 + 1/11)% = (100/11)/100 = 1/11, the correct answer choice must be a MULTIPLE OF 11.
Of the remaining answer choices, only B is a multiple of 11.

The correct answer is B.