Question Detail

A student got twice as many sums wrong as he got right. If he attempted 48 sums in all, how many did he solve correctly ?

Answer: Option B

Explanation:

Suppose boy got x sums right and 2x sums wrong,
then,
x+2x = 48
=> 3x = 48
=> x = 16

1. A student got twice as many sums wrong as he got right. If he attempted 48 sums in all, how many did he solve correctly ?

Answer: Option B

Explanation:

Suppose boy got x sums right and 2x sums wrong,
then,
x+2x = 48
=> 3x = 48
=> x = 16

2. In a class, there are 18 boys who are over 160 cm tall. If these constitute three-fourths of the boys and the total number of boys is two-thirds of the total number of students in the class, what is the number of girls in the class ?

Answer: Option B

Explanation:

Let the number of boys be x.
Then, 3/4 x = 18
=> x = 24

If total number of students is y, then
2/3 y = 24
=> y = 36

Number of girls in class = y - x
= 36 - 24 = 12

3. In a chess tournament each of six players will play every other player exactly once. How many matches will be played during the tournament ?

Answer: Option B

Explanation:

I. matches of first player with other 5 players
II. matches of second player with 4 players other than the first player
III. matches of third player with 3 players other than the first player and second player.
IV. matches of fourth player with 2 players other than the first player, second player and third player.
V. matches of fifth player with 1 player other than the first player, second player, third player and fourth player.

So total matches will be 5+4+3+2+1 = 15

4. A father is now three times as old as his son. Five years back, he was four times as old as his son. The age of the son is :

Answer: Option B

Explanation:

Let son's age be x then father's age is 3x
Five years ago, father's age = 3x-5 and son's age x-5
So, 3x-5 = 4(x-5)
=> 3x-5 = 4x-20
=> x = 15

5. In a caravan, in addition to 50 hens, there are 45 goats and 8 camels with some keepers. If the total number of feet be 224 more than the number of heads in the caravan, the number of keepers is

Answer: Option D

Explanation:

Let the number of keepers be x.
Then, total number of feet = 2*50+4*45+4*8+2x
= 2x + 312

Total number of heads = 50+45+8+x = 103 + x
Now, (2x+312) = (103+x)+224
=> x = 15