Quantitative Aptitude - Arithmetic Ability Questions

The given number series is 96, 95, 87, 78, ? 

It follows a pattern that,

$$\begin{gathered} 96 \\ 96 - 12 = 95 \\ 95 - 23 = 95 - 8 = 87 \\ 87 - 32 = 87 - 9 = 78 \\ 78 - 43 = 78 - 64 = 14 \end{gathered}$$

Hence, the next number in the given number series is 14.

i) Let the ages of the five members at present be a, b, c, d & e years. 

And the age of the new member be f years. 

ii) So the new average of five members' age = (a + b + c + d + f)/5 ------- (1) 

iii) Their corresponding ages 3 years ago = (a-3), (b-3), (c-3), (d-3) & (e-3) years 

So their average age 3 years ago = (a + b + c + d + e - 15)/5 = x ----- (2) 

==> a + b + c + d + e = 5x + 15 

==> a + b + c + d = 5x + 15 - e ------ (3) 

iv) Substituting this value of a + b + c + d = 5x + 15 - e in (1) above, 

The new average is: (5x + 15 - e + f)/5 

Equating this to the average age of x years, 3 yrs, ago as in (2) above, 

(5x + 15 - e + f)/5 = x 

==> (5x + 15 - e + f) = 5x 

Solving e - f = 15 years. 

Thus the difference of ages between replaced and new member = 15 years.

Let length of plot = L meters, then breadth = L - 20 meters

and perimeter = 2[L + L - 20] = [4L - 40] meters

[4L - 40]  * 26.50 = 5300

[4L - 40] = 5300 / 26.50 = 200

4L = 240

L = 240/4= 60 meters. 

The given series is 1 6 27 124 650

1

1 + 2 x 2 = 6

6 + 3 x 3 = 27

27 + 4 x 4 = 124

124 + 5 x 5 = 645 (NOT 650)

Hence, the odd man in the given number series is 650.

Given year is divided by 4, and the quotient gives the number of leap years.

Here, 100%4 = 25.

But, as 100 is not a leap year => 25 - 1= 24 leap years.