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April 27, 2021 - CSAT Quiz
1. If a two-digit positive integer has its digits reversed, the resulting integer differs from the original by 27. By how much do the two digits differ?
(a) 3
(b) 4
(c) 5
(d) 6
Solution:
Given that (10a + b) - (10b + a) = 27 --> 9a - 9b =27 --> a - b = 3.
(a) 3
2. Suppose the average weight of 9 persons is 50 kg. The average weight of the first 5 persons is 45 kg, whereas the average weight of the last 5 persons is 55 kg. Then the weight of the 5th person will be
(a) 45 kg
(b) 47.5 kg
(c) 50 kg
(d) 52.5 Kg
Solution:
Weight of fifth person = (5 × 45 + 5 × 55) – 9 × 50
= (225 + 275) – 450
= 500 – 450 = 50 kg
(c) 50 kg
3. In a city, 12% of households earn less than Rs. 30,000 per year, 6% households earn more than Rs. 2,00,000 per year, 22% households earn more than Rs. 1,00,000 per year and 990 households earn between Rs. 30,000 and Rs. 1,00,000 per year. How many households earn between Rs. 1,00,000 and Rs. 2,00,000 per year?
(a) 250
(b) 240
(c) 230
(d) 225
Solution:
(b) 240
4. There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first five such numbers, then what is the mean of all the thirteen numbers?
(a) 47
(b) 49
(c) 51
(d) 45
Solution:
(a) 47
Alternatively,
For an odd number of consecutive numbers the mean is the central number. Here mean of first five number is 39 which means that the third number is 39. For 13 consecutive numbers, mean shall be 7th number. Now third number is 39, fourth shall be 41, fifth shall be 43, sixth shall be 45 and seventh shall be 47.
5. There is a milk sample with 50% water in it. If 1/3rd of this milk is added to equal amount of pure milk, then water in the new mixture will fall down to
(a) 25%
(b) 30%
(c) 35%
(d) 40%
Solution:
Since we have to take 1/3 of the solution therefore let us assume that the volume of solution was 90 L (i.e. something which we can easily divide in 3 parts).
Now one-third of this solution is taken. That means 30 L is taken. This 30 L will have 15 L milk and 15 L water (because water and milk are 50% and 50%).
Now this solution of 30 L (15 L milk + 15 L water) is added to equal amount of pure milk. Thus 30 L of pure milk is added. Thus finally we have in the new mixture: 45 L milk + 15 L water. Thus water is 15/60 parts = ¼ parts which is 25%.
Thus the answer is option (a):
(a) 25%
(b) 240
4. There are thirteen 2-digit consecutive odd numbers. If 39 is the mean of the first five such numbers, then what is the mean of all the thirteen numbers?
(a) 47
(b) 49
(c) 51
(d) 45
Solution:
(a) 47
Alternatively,
For an odd number of consecutive numbers the mean is the central number. Here mean of first five number is 39 which means that the third number is 39. For 13 consecutive numbers, mean shall be 7th number. Now third number is 39, fourth shall be 41, fifth shall be 43, sixth shall be 45 and seventh shall be 47.
5. There is a milk sample with 50% water in it. If 1/3rd of this milk is added to equal amount of pure milk, then water in the new mixture will fall down to
(a) 25%
(b) 30%
(c) 35%
(d) 40%
Solution:
Since we have to take 1/3 of the solution therefore let us assume that the volume of solution was 90 L (i.e. something which we can easily divide in 3 parts).
Now one-third of this solution is taken. That means 30 L is taken. This 30 L will have 15 L milk and 15 L water (because water and milk are 50% and 50%).
Now this solution of 30 L (15 L milk + 15 L water) is added to equal amount of pure milk. Thus 30 L of pure milk is added. Thus finally we have in the new mixture: 45 L milk + 15 L water. Thus water is 15/60 parts = ¼ parts which is 25%.
Thus the answer is option (a):
(a) 25%
POSTED ON 27-04-2021 BY ADMIN
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