Aptitude Day 326

Problems on Percentage:

1. A student’s mathematics test had 80 problems. i.e., 20 arithmetic, 40 algebra and 20 geometry problems.  Although she answered 60% of the arithmetic, 40% of the algebra and 40% of the geometry problems correctly, she did not pass the test because she got less than 60% of the problems right. How many more questions she would have needed to answer correctly to earn a 60% passing grade?

Solution:

                  Number of questions attended correctly = 60% of 20 + 40% of 40 + 40% of 20 

                                                                                   = 60/20 + 40/40 + 40/20

                                                                                   = 3+1+2 = 6.

                  60% of 80 = 48.

                   Required number of questions = 48-6 = 42.

2. If 60% of (x-y) = 40% of (x+y), then what percent of x is y?

Solution:

                 60/100*(x-y) = 40/100* (x+y)

                 By solving this equation, we get x = 5y.

                y/x * 100 = y/5y * 100 = 20%.