Answer this question:A party hall has 3 decorative light bulbs; a red light bulb which comes on every 2 seconds, a green one every 3 seconds and a blue one every 4 seconds. If they are put on at the same time, what is the shortest time after which the three bulbs will be on at the same time?
The blue light bulb comes on every 2 seconds so it will be on after 2, 4, 6, 8, 10, 12, 14... seconds (multiples of 2). The red light bulb comes on every 3 seconds so it will be on after 3, 6, 9, 12, 15, 18... seconds (multiples of 3). The blue light bulb comes on every 4 seconds so it will be on after 4, 8, 12, 16, 20... seconds (multiples of 4). The shortest time after which all three will be on is 12 seconds which is the least common multiple of the set of multiples.
The answer is 12.

Answer this question:Jenna is on a road trip. She drives for 2 hours at 60mph. She takes a bathroom break, and then she continues driving for 3 hours at 50 mph. She can drive for 30 miles on one gallon of gas. If one gallon of gas costs $2, how much money does she spend on gas for her trip?
First she drives 2 hours * 60 mph = 120 miles. Then she drives 3 hours * 50 mph = 150 miles. The total miles driven is 120 + 150 = 270 miles. Jenna uses 270 / 30 = 9 gallons of gas. The cost of gas is 9 * $2 = $18.
The answer is 18.

Answer this question:After eating half of the number of fruits he had, Martin remained with twice as many oranges as limes. If he has 50 oranges now, how many fruits did he initially have?
Since the number of oranges that Martin has now is twice the number of limes, there are 50 / 2 = 25 limes. The number of fruits she has now is 50 oranges + 25 limes = 75. If she had eaten half of the number of fruits that she had, initially Martin had 2 * 75 = 150 fruits.
The answer is 150.

Answer this question:A choir was singing a song that involved 30 singers. In the first verse, only half of them sang. In the second verse, a third of the remaining singers joined in. How many people joined in the final third verse that the whole choir sang together?
In the first verse, 30 / 2 = 15 singers sang. In the second verse, 15 / 3 = 5 singers joined in. In the final verse, 30 - 15 - 5 = 10 singers joined for the whole choir to sing together.
The answer is 10.