SSC CGL Ratio and Average Practice Test 27

1. If A:B = 5:7 and B:C = 6:11, then A:C is:

• A. 30:77 (Correct)
• B. 35:66
• C. 42:55
• D. 55:72

Explanation: Make B common: A:B = 30:42 and B:C = 42:77, so A:C = 30:77.

2. The average of 12 numbers is 38. If one number 49 is replaced by 25, the new average is:

• A. 34
• B. 35
• C. 36 (Correct)
• D. 37

Explanation: Original sum = 456. New sum = 456 - 49 + 25 = 432. New average = 432/12 = 36.

3. The average age of 8 students is 15 years. When their teacher joins, the average becomes 17 years. Find the teacher's age.

• A. 31 years
• B. 33 years (Correct)
• C. 35 years
• D. 37 years

Explanation: Total age of 8 students = 120. Total age of 9 people = 153. Teacher's age = 33 years.

4. A vessel has milk and water in the ratio 7:5. After adding 12 L water, the ratio becomes 7:8. Find the initial quantity of mixture.

• A. 36 L
• B. 42 L
• C. 48 L (Correct)
• D. 54 L

Explanation: Let milk = 7x and water = 5x. After adding water, 7x:(5x+12) = 7:8, so x = 4. Initial mixture = 12x = 48 L.

5. A and B have amounts in the ratio 4:5. If Rs. 18 is added to each, the ratio becomes 5:6. Find B's original amount.

• A. Rs. 72
• B. Rs. 81
• C. Rs. 90 (Correct)
• D. Rs. 96

Explanation: Let amounts be 4x and 5x. (4x+18)/(5x+18)=5/6 gives x=18. B = 5x = 90.

6. A class has 30 boys with average marks 64 and 20 girls with average marks 74. Find the average marks of the class.

• A. 66
• B. 68 (Correct)
• C. 70
• D. 72

Explanation: Combined average = (30 x 64 + 20 x 74)/50 = 3400/50 = 68.

7. P invests Rs. 5,000 for 12 months, Q invests Rs. 8,000 for 9 months and R invests Rs. 10,000 for 6 months. If total profit is Rs. 48,000, R's share is:

• A. Rs. 14,000
• B. Rs. 15,000 (Correct)
• C. Rs. 16,000
• D. Rs. 18,000

Explanation: Capital-time ratio = 60000:72000:60000 = 5:6:5. R gets 5/16 of 48000 = 15000.

8. The numbers of Rs. 1, Rs. 2 and Rs. 5 coins are in the ratio 3:4:5. If the total value is Rs. 720, how many Rs. 5 coins are there?

• A. 80
• B. 90
• C. 100 (Correct)
• D. 120

Explanation: Value = 3x + 8x + 25x = 36x = 720, so x = 20. Rs. 5 coins = 5x = 100.

9. The ages of A and B are in the ratio 3:5. After 8 years, the ratio will be 5:7. Find A's present age.

• A. 10 years
• B. 12 years (Correct)
• C. 14 years
• D. 16 years

Explanation: Let ages be 3x and 5x. (3x+8)/(5x+8)=5/7 gives x=4. A's age = 12 years.

10. A person travels 60 km at 30 km/h and returns at 45 km/h. Find his average speed for the whole journey.

• A. 34 km/h
• B. 35 km/h
• C. 36 km/h (Correct)
• D. 37.5 km/h

Explanation: For equal distances, average speed = 2ab/(a+b) = 2 x 30 x 45 / 75 = 36 km/h.

11. The average of five consecutive odd numbers is 47. Find the largest number.

• A. 49
• B. 51 (Correct)
• C. 53
• D. 55

Explanation: For five consecutive odd numbers, the average is the middle number. Numbers are 43, 45, 47, 49 and 51.

12. A sum of Rs. 9,600 is divided among A, B and C in the ratio 5:7:12. Find B's share.

• A. Rs. 2,400
• B. Rs. 2,800 (Correct)
• C. Rs. 3,000
• D. Rs. 3,200

Explanation: Total parts = 24. B's share = 7/24 of 9600 = 2800.

13. The average of 40 values is 52. Later, it is found that 62 was wrongly read as 26. Find the correct average.

• A. 52.6
• B. 52.8
• C. 52.9 (Correct)
• D. 53.0

Explanation: Sum increases by 62 - 26 = 36. Average increases by 36/40 = 0.9. Correct average = 52.9.

14. Tea worth Rs. 180/kg is mixed with tea worth Rs. 240/kg in the ratio 3:2. Find the average cost per kg.

• A. Rs. 198
• B. Rs. 204 (Correct)
• C. Rs. 210
• D. Rs. 216

Explanation: Average cost = (3 x 180 + 2 x 240)/5 = 1020/5 = 204.

15. Two numbers are in the ratio 11:14 and their difference is 45. Find the smaller number.

• A. 150
• B. 155
• C. 160
• D. 165 (Correct)

Explanation: Difference = 3 parts = 45, so 1 part = 15. Smaller number = 11 x 15 = 165.