The length of a rectangle is increased by 25%. By what percentage should the width be decreased so that the area of the rectangle remains unchanged?
বিকল্পসমূহ (নিজের উত্তর যাচাই করতে ক্লিক করুন):
সঠিক উত্তর
2 (20%)
বিস্তারিত ব্যাখ্যা ও বিশ্লেষণ:
Solution:
We can let the original length = 4, and the original width = 10.
So the original area is 40.
When the length increases by 25%
we have 4 × 1.25 = 5
Thus, for the area to remain 40, the width must be 8.
Since {(8 - 10)/10} × 100 = - 20, we see that 8 is 20 percent less than 10. In other words, the width has to decrease by 20%.
