Quantitative Aptitude - Arithmetic Ability Questions

Total weight of 50 boys = 45 X 50 = 2250

Average weight of 49 boys = 44.9

Total weight of 49 boys = 44.9 X 49 = 2200.1

Weight of boy who left the class=2250–2200.1=49.9

Working efficiency of both typist together = 100/6 = 16.66%

Let the efficiency of first typist be x and second typist be (16.66 –x)

First typist for 4 minute + second tyoistfor 6 minute = 80% work

⇒4x + (16.66 –x) X 6 = 80%

⇒4x + 100% -6x = 80%,

⇒x = 10%

First typist typed 10% per minute, second typst typed (16.66 –10) = 6.66% per minute

Slowest is second typist complete whole job in 100/6.66 = 15.01 = 15 minute

Here  18 in decimal means 8th part in 1.

We know that 110 = 0.1

Then,   18 = ?

=> $$\begin{gathered} ? = 18 x 0.1110 \\ = 0.1 x 108 \\ = 0.54 \\ 18= 0.125 \end{gathered}$$

We know, the perimeter of a triangle = sum of all the sides of a triangle = a + b + c

Here given that sides a = 38, b= 36 and c = 18

Now, perimeter of the triangle = a + b + c = 38 + 36 + 18 = 92 units.

In circumcstances word there are 3C's, 2S's, I, U,R, T, A, N, E

Total = 13 letters

But last letter must be N

Hence, available places = 12

In that odd places = 1, 3, 5, 7, 9, 11

Owvels = 4

This can be done in 6P4 ways 

Remaining 7 letters can be arranged in 7!/3! x 2! ways

Hence, total number of ways = 6P4 x 7!/3! x 2! = 360 x 5040/12 = 1,51,200 ways.

A prime number is a whole number greater than 1 whose only factors are 1 and itself.

Factors of 5 are 1, 5

Factors of 11 are 1, 11

Factors of 21 are 1, 3, 7, 21

Factors of 37 are 1, 37.

Hence, according to the definition of a prime number, 21 is not a prime number as it has more than two factors.