Problem-solving Questions and Answers
Practice ModeShowing 10 of 50 questions
Q31
If 12 workers complete a work in 15 days, 10 workers will complete in:
Answer: Option A
Explanation: Work = 12 × 15 = 180 worker-days, Days for 10 workers = 180/10 = 18 days
Q32
A bag contains 3 red, 4 green, 5 blue balls. Probability of picking green = ?
Answer: Option B
Explanation: Total = 3+4+5=12, Probability = 4/12 = 1/3
Q33
A train 100 m long passes a man in 5 seconds. Speed = ?
Answer: Option A
Explanation: Speed = 100/5 = 20 m/s = 20 × 18/5 = 72 km/h
Q34
A can do a work in 15 days, B in 20 days. If they work on alternate days, starting with A, total days = ?
Answer: Option B
Explanation: 2 days work = 1/15 + 1/20 = 7/60, In 16 days = 56/60, Remaining 4/60 = 1/15 done by A in 1 day, Total = 17 days
Q35
A can do a piece of work in 6 days, B in 8 days. They work together for 3 days. Fraction of work left = ?
Answer: Option B
Explanation: Combined 1 day work = 1/6 + 1/8 = 7/24, Work in 3 days = 21/24 = 7/8, Left = 1 - 7/8 = 1/8
Q36
A sum of money lent at 4% per annum SI amounts to ₹2600 in 2 years. Find principal.
Answer: Option A
Explanation: SI for 2 years = 8% of P, Amount = 108% of P = 2600, P = 2600/1.08 ≈ ₹2407 ≈ ₹2500 (nearest option)
Q37
The speed of a boat in still water is 16 km/h. If speed of stream is 2 km/h, downstream speed = ?
Answer: Option C
Explanation: Downstream = 16 + 2 = 18 km/h
Q38
A shopkeeper gains 25% by selling an article at ₹500. CP = ?
Answer: Option A
Explanation: CP × (1 + 25/100) = 500 → CP × 1.25 = 500 → CP = 500/1.25 = ₹400
Q39
If the cost of 12 pens is ₹60, cost of 20 pens = ?
Answer: Option B
Explanation: Cost of 1 pen = 60/12 = ₹5, Cost of 20 pens = 20 × 5 = ₹100
Q40
A can do 1/3 of a work in 4 days. Time to complete whole work = ?
Answer: Option A
Explanation: 1/3 work in 4 days → Whole work in 4 × 3 = 12 days