A lamppost is divided into three parts, the first part is (1/3)rd of the whole length, second (3/8)th of the first and the third is 6 m 50 cm. The length of the lamppost is?

Let the length of lamppost = L m
Then,first part = L/3
and second part = (3/8) x L/3 = L/8
and third part = 6 m 50 cm = 6.50 m
First part + second part + Third part = length of lamppost
⇒ L/3 + L/8 + 6.5 = L
⇒ L - L/3 - L/8 =6.5
⇒ (24L - 8L - 3L)/24 = 6.5
⇒ 13L/24 = 6.5
∴ L = (65.x 24)/13 = 12 m