Problem Solving MCQ Set 30

Question: A red light flashes 3 times per minute and a green light flashes 5 times in two minutes at regular intervals. If both lights start flashing at the same time, how many times do they flash together in each hour?

1. 30
2. 24
3. 20
4. 60

Question: A and B can do a piece of work in 21 and 24 days respectively. They started the work together and after some days A leaves the work and B completes the remaining work in 9 days. After how many days did A leave?

1. 5
2. 7
3. 8
4. 6

Question: Ram, who is half as efficient as Krish, will take 24 days to complete a work if he worked alone. If Ram and Krish worked together, how long will they take to complete the work?

1. 16 days
2. 12 days
3. 8 days
4. 18 days

Question: A number is selected at random from first thirty natural numbers. What is the chance that it is a multiple of either 3 or 13?

1. 17/30
2. 2/5
3. 11/30
4. 4/15

Question: What is the probability of getting at least one six in a single throw of three unbiased dice?

1. 1 / 6
2. 125 / 216
3. 1 / 36
4. 91 / 216

Question: What is the probability that a two digit number selected at random will be a multiple of '3' and not a multiple of '5'?

1. 2 / 15
2. 4 / 15
3. 1 / 15
4. 4 / 90