self Maths Puzzle

What is the speed of the boat in still water?

I.

The speed downstream is 12 kmph.

II.

The speed upstream is 4 kmph.

III.

In a to and fro journey between two points, the average speed of the boat was 6 kmph.

A. I and II only
B.All I, II and III
C.III,and either I or II
D.Any two of the three

Read Solution (Total 1)

From I and II, speed of boat in still water = 1/2 X (12 + 4) km/hr

= 8 km/hr
From II and III, we get:

Using average speed = 2xy /(x+y), we get: 2 x 4 x y /(4+y)= 6

=> 8y = 24 + 6y

=> y = 12.

Required speed = 1/2 X (12 + 4) km/hr = 8 km/h r.

Similarly, I and III also give the answer.

Correct answer is (D).
12 years agoHelpfull: Yes(4) No(0)

self Other Question

Midas has boxes in three sizes: large, medium, and small. He puts 11 large boxes on a table. He leaves some of these boxes empty, and in all the other boxes he puts 8 medium boxes. He leaves some of these medium boxes empty, and in all the other medium boxes he puts 8 (empty) small boxes. Now, 102 of all the boxes on the table are empty.
How many boxes has Midas used in total? Ravi, Gagan and Nitin are running a business firm in partnership. What is Gagan's share in the profit earned by them?

I.

Ravi, Gagan and Nitin invested the amounts in the ratio of 2 : 4 : 7.

II.

Nitin's share in the profit is Rs. 8750.

A. I alone sufficient while II alone not sufficient to answer
B. II alone sufficient while I alone not sufficient to answer
C. Either I or II alone sufficient to answer
D. Both I and II are not sufficient to answer
E. Both I and II are necessary to answer