Question
What is the average of the squares of the first 19 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
= (19 + 1) × (2 × 19 + 1) ÷ 6
= 20 × 39 ÷ 6
= 130
Find the value of ‘x’ if x% of 600 + {1440 ÷ x of 16} × 8 = 156
How many 3-digit numbers are divisible by 6 or 9?
The diameter of the base of a right circular cone is 4.2 cm and its height is 10 cm. calculate the volume of the cone.
Find the LCM of x2 - 3x + 2 and x2 - 5x + 6
The sentence below has a word in which the letters are jumbled up. Rearrange the letters of that word, written in capital letters, to form the correct w...
A man is 60% more efficient than a boy. Together, two boys and one man can finish a task in 15 days. How many boys would be needed to complete the same ...
If A:B = 5:8 and C:B = 4:9 then find the value of (A:B:C) .
A tradesman gives 6% discount on the marked price and 1 article free with every 24 articles bought and still gains 25%. If the marked price is 28% more ...
A cuboidal box has dimensions of length = 18 cm, breadth = 15 cm, and height = 10 cm. If the breadth is increased by 20% and the height is decreased by ...
If '+' means '-' , '-' means 'x' , 'x' means '÷' , '÷' means '+' , then what will be the value of ' 500 x 50 - 20 ÷ 50 + 40 ' = ?
...
Relevant for Exams:
