From a point P on a level ground, the angle of elevation of the top tower is 30°. If the tower is 100 m high, the distance of point P from the foot of the tower is:

Question:
X and Y can do a piece of work in 20 days and 12 days respectively. X started the work alone and then after 4 days Y joined him till the completion of the work. How long did the work last?

[A].

6 days

[B].

10 days

[C].

15 days

[D].

20 days

Answer: Option B

Explanation:

Work done by X in 4 days =		1	x 4		=	1	.
		20				5

Remaining work =		1 –	1		=	4	.
			5			5

(X + Y)’s 1 day’s work =		1	+	1		=	8	=	2	.
		20		12			60		15

Now,	2	work is done by X and Y in 1 day.
	15

So,	4	work will be done by X and Y in		15	x	4		= 6 days.
	5			2		5

Hence, total time taken = (6 + 4) days = 10 days.

Question:
Sakshi can do a piece of work in 20 days. Tanya is 25% more efficient than Sakshi. The number of days taken by Tanya to do the same piece of work is:

[A].

15

[B].

16

[C].

18

[D].

25

Answer: Option B

Explanation:

Ratio of times taken by Sakshi and Tanya = 125 : 100 = 5 : 4.

Suppose Tanya takes x days to do the work.

5 : 4 :: 20 : x    x =		4 x 20
		5

x = 16 days.

Hence, Tanya takes 16 days to complete the work.