Q3 of 180 Page 3

The mean of first ‘n’ odd natural numbers is . Then n =

First ‘n’ odd natural numbers are

1, 3, 5, …, (n terms)

This is an AP with

First term, a = 1

Common difference, d = 2

∴ Sum of first ‘n’ terms

⇒ S_n = n²

Mean of first ‘n’ odd natural numbers

⇒ n = 81

Hence, Option B is correct.

O is the centre of a circle of radius 8 cm. The tangent at a point A on the circle cuts a line through O at B such that AB = 15 cm. Find OB.

Given that HCF (96,404) is 4, find the LCM (96,404).

The centroid of the triangle whose vertices (1, 4), (-1, -1), (3, -2) is.

The value of 2tan²45° + cos²30° + sin²60° is