4370.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 ?
12
16
18
24
Explanation:
Suppose the boy got x sums right and 2x sums wrong.
Then, x + 2x = 48 3x = 48 x = 16.
Suppose the boy got x sums right and 2x sums wrong.
Then, x + 2x = 48 3x = 48 x = 16.
4371.David gets on the elevator at the 11th floor of a building and rides up at the rate of 57 floors per minute. At the same time, Albert gets on an elevator at the 51st floor of the same building and rides down at the rate of 63 floors per minute. If they continue travelling at these rates, then at which floor will their paths cross ?
19
28
30
37
4372.I have a few sweets to be distributed. If I keep 2, 3 or 4 in a pack, I am left with one sweet. If I keep 5 in a pack, I am left with none. What is the minimum number of sweets I have to pack and distribute ?
25
37
54
65
Explanation:
Clearly, the required number would be such that it leaves a remainder of 1 when divided by 2, 3 or 4 and no remainder when divided by 5. Such a number is 25.
Clearly, the required number would be such that it leaves a remainder of 1 when divided by 2, 3 or 4 and no remainder when divided by 5. Such a number is 25.
4373.If a clock takes seven seconds to strike seven, how long will it take to strike ten ?
7 seconds
9 seconds
10 seconds
None of these
4374.In a group of cows and hens, the number of legs are 14 more than twice the number of heads. The number of cows is
5
7
10
12
Explanation:
Let the number of cows be x and the number of hens be y.
Then, 4x + 2y = 2 (x + y) + 14 4x + 2y = 2x + 2y + 14 2x = 14 x = 7.
Let the number of cows be x and the number of hens be y.
Then, 4x + 2y = 2 (x + y) + 14 4x + 2y = 2x + 2y + 14 2x = 14 x = 7.
4375.A father tells his son, “I was of your present age when you were born”. If the father is 36 now, how old was the boy five years back ?
13
15
17
20
Explanation:
Let the fathers age be x and the sons age be y.
Then, x – y = y or x = 2y,
Now, x = 36. So, 2y = 36 or y = 18.
Therefore Sons present age = 18 years.
So, sons age 5 years ago = 13 years.
Let the fathers age be x and the sons age be y.
Then, x – y = y or x = 2y,
Now, x = 36. So, 2y = 36 or y = 18.
Therefore Sons present age = 18 years.
So, sons age 5 years ago = 13 years.
4376.A fires 5 shots to Bs 3 but A kills only once in 3 shots while B kills once in 2 shots. When B has missed 27 times, A has killed
30 birds
60 birds
72 birds
90 birds
4377.In a class, 3/5 of the students are girls and rest are boys. If 2/9 of the girls and 1/4 of the boys are absent, what part of the total number of students is present ?
17/25
18/49
23/30
23/36
4378.In a family, a couple has a son and a daughter. The age of the father is three times that of his daughter and the age of the son is half of that of his mother. The wife is 9 years younger to her husband and the brother is seven years older than his sister. What is the age of the mother ?
40 years
45 years
50 years
60 years
Explanation:
Let the daughters age be x years.
Then, fathers age = (3x) years.
Mothers age = (3x – 9) years; Sons age = (x + 7) years.
So, x + 7 = (3x-9)/2 2x + 14 = 3x – 9 x = 23.
Therefore Mothers age = (3X – 9) = (69 – 9) years = 60 years.
Let the daughters age be x years.
Then, fathers age = (3x) years.
Mothers age = (3x – 9) years; Sons age = (x + 7) years.
So, x + 7 = (3x-9)/2 2x + 14 = 3x – 9 x = 23.
Therefore Mothers age = (3X – 9) = (69 – 9) years = 60 years.
4379.If a 1 mm thick paper is folded so that the area is halved at every fold, then what would be the thickness of the pile after 50 folds ?
100 km
1000 km
1 million km
1 billion km