Question
What is the average of the squares of the first 25 natural
numbers?Solution
Sum of squares of first 'n' natural numbers = n × (n + 1) × (2n + 1) ÷ 6
So, average = n × (n + 1) × (2n + 1) ÷ 6n = (n + 1) × (2n + 1) ÷ 6
= (25 + 1) × (2 × 25 + 1) ÷ 6
= 26 × 51 ÷ 6
= 221
Select the set of letters that when sequentially placed in the blanks of the given letter series will complete the series.
_ x y _ w _ y z w x _ _ w _ _ z
Drake : Duck : : Wizard : ?Â
If 23 @ 18 = 9 and 29 @ 24 = 21', then 24 @ 19 = ?'. What will come in place of question mark?
Seven friends, A, B, C, D, E, F and G are sitting in a straight line facing the same direction. E is sitting at one extreme end. E is sitting second to ...
Choose the word which is different from the rest
Four letter-clusters have been given, out of which three are alike in some manner and one is different. Select the letter-cluster that is different.
- Select the word-pair in which the two words are related in the same way as are the two words in the following word-pair:
Sparrow : Bird Number of letters skipped in between adjacent letters goes on increasing successively by one in the series. Identify the set following the above rule.
Select the number -pair from the given options that shares a similar relationship as the given number-pair.
192-108
‘Confined spaces’ is related to ‘Claustrophobia’ in the same way as ‘Insects’ is related to ‘______’.
Relevant for Exams:
