Percentage Decrease

[tonebeeze]

If the length and width of a rectangular diagram 12 inches by 8 inches are to be reduced by the same percent so that the diagram will exactly fit into a rectangular space 4.5 inches by 3 inches, by what percent should the dimensions by reduced?

a. 25%
b. 37.5%
c. 62.5%
d. 75%
e. 87%

Any good study tips regarding mastering percentage increase and decrease problems?

OA = C

[HSPA]

How to avoid chosing option B in such questions... I mean when doing quick 4.5 is 37.5% of 12... so in a hurry I chose B... but question asks by what percent it shall be reduced ... 62.5

[tonebeeze]

That's exactly what I did. When you look at the problem, the answer is intuitively easy, but the language of the problem is tricky. I missed these problems with minor careless errors.

[garuhape]

In this case you have to figure out which of the two sides you have to reduce more.

1. 12inches are reduced to 4.5 inches. Therefore, the new side is only 4.5/12*100% which is (4.5*8.5)/100 = 38.25%

2. 8 inches are reduced to 3 inches. Therefore, you have to multiply both by 12.5 to get % since 8*12.5=100. The result is 37.5/100 which is 37.5%. That's why it has to be reduced by 100%-37.5% which is 62.5%