Quantitative Aptitude - Arithmetic Ability Questions

Given that the waste tap can empty the filled tank in 32 min.

Now, the rate at which the waste tap can empty the tank = (40 + 60)8/32 = 100/4 = 25 lit/min.

Total number of exams written by 100 students = 48 + 45 + 38 = 131
Now let us say x members are writing only 1 exam, y members are writing only 2 exams, z members are writing only 3 exams.
Therefore, x + 2y + 3z = 131 also x + y + z = 100.
Given that z = 5. So x + 2y = 116 and x + y = 95.
Solving we get y = 21.
So 21 members are writing exactly 2 exams.

Slant surface of a pyramid=1/2 perimeter of base slantheight

=1/2 x (4  x Side of squarebase) x Slantheight

Given Prabhas is twice as good a workman as Rana.

Prabhas finishes the work in 3 hrs

=> Rana finishes the work in 6 hrs.

Number of hours required together they could finish the work

= 3 x 6 / 3 + 6

= 18/9

= 2 hrs.

From the given series of numbers, if half of the second highest number is subtracted from the third highest number, what will be the value ?

Now arranging the given numbers in descending order.
837 746 519 495 328

519 - 746/2 = 519 - 373 = 146.

ST candidates vacancies can be filled by C35 ways = 10 

Remaining vacancies are 5 that are to be filled by 12 

=> C512= (12x11x10x9x8)/(5x4x3x2x1) = 792 

Total number of filling the vacancies = 10 x 792 = 7920

Michel earns Rs. 135 by investing Rs. 1620
To earn Rs. 8 how much he have to invest...?

= (8 x 1620)/135 = Rs. 96