Quantitative Aptitude - Arithmetic Ability Questions

A : B = 100 : 80.

A : C = 100 : 72.

B:C = B/A*A/C = 80/10*100/72 = 10/9 = 100/90 = 100:90

 B can give C 10 points

729 = 9 x 9 x 9

=> Cube root of 729 = 9

Now, required square of 9 = 9 x 9 = 81.

Let the speed of boat in still water is ‘x’ km/hr & that of stream is ‘y’ km/hr.
Then, ATQ
(x+y)/y = 9/1 9y = x + y
x = 8y
y = 3 km/hr
So, x = 24 km/hr
Upstream speed = 24-3 = 21 km/hr
Hence, distance travelled upstream in 5 hours = 21*5 = 105 km.

Given total number of students in the class = 21

So each student will have 20 greeting cards to be send or receive (21 - 1(himself))

Therefore, the total number of greeting cards exchanged by the students = 20 x 21 = 420.

Since two of the eight first class petty officers are to fill two different offices, we write 8P2=56

Then, two of the six second class petty officers are to fill two different offices; thus, we write 6P2 =30

The principle of choice holds in this case; therefore, the members have 56 x 30 = 1680 ways to select the required office holders

The given 3b - 7 < 32 can be solved as

3b - 7 < 32

3b < 39

b < 13.

-10+10-10*10100 % = -1%

 Decrease in revenue = 1%