Question

A lamp post has half of its length in mud and `1/3` of its length in water.

(i) What fraction of its length is above the water?
(ii) If `3 1/3` m of the lamp post is above the water, find the whole length of the lamp post.

Answer 1

(i) Let length of the post = 1 m

then length of post in mud =`1/2` m

and length of post in water = `1/3` m

∴ Length of post above the water

`= 1 - (1/2 + 1/3) = 1 - ((3 + 2)/6)`

`= 1 - 5/6 = (6 - 5)/6 = 1/6` m

(ii) But length of post above water

`= 3 1/3 "m" = 10/3 "m"`

∴ `1/6`th of total length = `10/3` m

∴ Total length = `10/3 xx 6/1` = 20 m