Problem-solving Questions and Answers
Practice ModeShowing 10 of 50 questions
Q11
A can do a work in 20 days, B in 30 days. They work together for 10 days. Work left is:
Answer: Option D
Explanation: A's 1 day work = 1/20, B's 1 day work = 1/30, Combined 1 day work = 1/20 + 1/30 = 1/12, Work in 10 days = 10/12 = 5/6, Left = 1 - 5/6 = 1/6
Q12
Two trains start from stations A and B towards each other. They meet after 5 hours. If distance is 500 km and speed of one train is 50 km/h, find speed of other.
Answer: Option A
Explanation: Relative speed = 500/5 = 100 km/h, Other train speed = 100 - 50 = 50 km/h
Q13
A man borrows ₹5000 at 10% simple interest. Interest after 2 years = ?
Answer: Option A
Explanation: SI = (5000 × 10 × 2)/100 = ₹1000
Q14
A bag contains 5 red, 7 blue, and 8 green balls. Probability of picking a red ball = ?
Answer: Option A
Explanation: Total balls = 5+7+8 = 20, Probability = 5/20 = 1/4
Q15
A sum of money doubles itself at 10% per annum simple interest in 10 years. Find rate.
Answer: Option A
Explanation: SI = P, P = (P × R × 10)/100 → 1 = 10R/100 → R = 10%
Q16
A man divides 420 sweets among 3 children in ratio 2:3:4. Find the share of second child.
Answer: Option B
Explanation: Total parts = 2+3+4 = 9, Share of second = (3/9) × 420 = 140
Q17
If 8 men can do a work in 12 days, how long will 6 men take?
Answer: Option A
Explanation: Work = 8 × 12 = 96 man-days, Days for 6 men = 96/6 = 16 days
Q18
A car covers half distance at 60 km/h and remaining at 40 km/h. Average speed = ?
Answer: Option B
Explanation: Average speed = 2 × (60 × 40)/(60+40) = 2 × 2400/100 = 48 km/h
Q19
A bag has 10 white and 15 black balls. Probability of drawing black = ?
Answer: Option B
Explanation: Total = 10+15 = 25, Probability = 15/25 = 3/5
Q20
If a sum of ₹8000 is lent at 5% per annum simple interest, interest in 3 years = ?
Answer: Option A
Explanation: SI = (8000 × 5 × 3)/100 = ₹1200