Question

What will come in place of question mark (?) in the following number series?81, 82, 42, 15, ?(a) 3.75(b) 4.75(c) 5.75(d) 5.25(e) 6.75

Answer 1

(b) 4.75

explanation : 81*1/1+1=82

82*1/2+1=42

42*1/3+1=15

15*1/4+1=4.75

Answer 2

Answer: The correct answer is Option(B) that is 4.75.

Step-by-step explanation:

Given that:

A number series has been given here as follows-

81, 82, 42, 15, ?

And the last number in the series has been asked.

Finding the missing number:

Start with the first number- 81

Now how to get 82 from 81

let use, 81*(1/1)+1=82

Similarly for all other numbers in the series, we get;

82*(1/2)+1=42

42*(1/3)+1=15

Fraction used here for multiplication in the original number of the series is (1/1), (1/2), (1/3), (1/4) and so on.

and 1 is being added to each original number after the multiplication.

So, for the last number:

15*(1/4)+1=4.75

Hence, the correct answer is Option(B) that is 4.75.