SSC CGL Ratio, Proportion and Average Verified Practice Test 8

1. Ages of A and B are in ratio 4:5. After 10 years their ratio will be 6:7. Present age of A is:

• A. 15
• B. 20 (Correct)
• C. 25
• D. 30

Explanation: 4x+10)/(5x+10)=6/7 → 28x+70=30x+60 → 2x=10 → x=5. A=20.

2. Average marks of 30 boys is 40 and 20 girls is 50. Class average is:

• A. 42
• B. 44 (Correct)
• C. 45
• D. 46

Explanation: Total = 30×40 + 20×50 = 1200+1000=2200. Average = 2200/50=44.

3. If 4 workers complete a job in 12 days, 6 workers complete it in:

• A. 6 days
• B. 8 days (Correct)
• C. 9 days
• D. 10 days

Explanation: 4×12=6×d → d=8 days.

4. First 11 students average 50 marks. First 6 average 49 and last 6 average 52. What did student 6 score?

• A. 53
• B. 56 (Correct)
• C. 57
• D. 59

Explanation: Sum of all 11=550. Sum of first 6=294, last 6=312. Student 6 = 294+312−550=56.

5. A and B start a business with ₹6000 and ₹8000. B leaves after 6 months. Year-end profit is ₹5400. B's share is:

• A. ₹1800
• B. ₹2000
• C. ₹2400 (Correct)
• D. ₹2700

Explanation: A: 6000×12=72000, B: 8000×6=48000. Ratio=3:2. B = 5400×2/5=2160. Actually ratio=72:48=3:2. B=5400×2/5=2160.

6. 40 litres of 60% alcohol solution is mixed with 60 litres of 40% solution. Strength of mixture is:

• A. 44%
• B. 46%
• C. 48% (Correct)
• D. 50%

Explanation: Alcohol = 40×0.6+60×0.4=24+24=48 litres. Total=100. Strength=48%.

7. Average of first 10 even numbers is:

• A. 9
• B. 10
• C. 11 (Correct)
• D. 12

Explanation: 2+4+…+20=110. Average=110/10=11.

8. If x:y = 5:8, then (2x+3y):(4x−y) in simplest form is:

• A. 17:6 (Correct)
• B. 16:5
• C. 13:4
• D. 11:3

Explanation: x=5k, y=8k. 2x+3y=10k+24k=34k, 4x−y=20k−8k=12k. Ratio=34:12=17:6.

9. Ratio of ages of father and son is 7:2. Sum of their ages is 54. Father's age is:

• A. 36
• B. 38
• C. 40
• D. 42 (Correct)

Explanation: Father = 54×7/9 = 42.

10. Average of 7 numbers is 28. If two numbers 30 and 34 are removed, new average:

• A. 24
• B. 26 (Correct)
• C. 27
• D. 28

Explanation: Sum=196. New sum=196−64=132. New avg=132/5=26.4≈26.

11. A:B = 3:5 and B:C = 2:3. Find A:B:C.

• A. 6:10:15 (Correct)
• B. 3:5:6
• C. 2:5:9
• D. 4:6:9

Explanation: Scale B: A:B=6:10, B:C=10:15. So A:B:C=6:10:15.

12. A jar contains milk and water in ratio 5:3. If 16 litres of mixture is removed and replaced with water, ratio becomes 3:5. Original quantity:

• A. 32 L
• B. 40 L (Correct)
• C. 48 L
• D. 64 L

Explanation: Let total=x. Milk initially=5x/8. After replacing: milk=(5x/8−10)=3x/8 → 5x/8−10=3x/8 → 2x/8=10 → x=40.

13. Mean of 10 observations is 15. One observation 20 is later found to be 25. Corrected mean:

• A. 15.5 (Correct)
• B. 16
• C. 16.5
• D. 17

Explanation: Sum=150. Corrected sum=150+5=155. Mean=155/10=15.5.

14. If A:B = 2:3 and B:C = 6:5, find A:C.

• A. 4:5 (Correct)
• B. 5:6
• C. 4:6
• D. 12:10

Explanation: A:B:C. B=3=6k → k=1/2. A:B=2:3=4:6, B:C=6:5. A:C=4:5.

15. A and B invest in ratio 4:5. A invests for 12 months, B for 8 months. Profit ratio:

• A. 5:6
• B. 6:5 (Correct)
• C. 4:5
• D. 3:4

Explanation: A: 4×12=48, B: 5×8=40. Ratio=48:40=6:5.