instruction:
You are given a math word problem and you are supposed to make use of mathematical concepts like probability, combinatorics, linear equations, sequences/series, or simple operators like addition, subtraction, division, or multiplication to answer the given question. Choose the best option from the 5 given options and report that option.
question:
Question: One-tenth of the students at a nursery school are 4 years old or older. If 20 students have not yet reached their third birthday, and a total of 50 students are not between 3 years old and 4 years old, how many children are in the nursery school?

 Option A: 150

 Option B: 300

 Option C: 450

 Option D: 490

 Option E: 620
answer:
Option B


question:
Question: How much time will it take for an amount of Rs. 900 to yield Rs. 81 as interest at 4.5% per annum of simple interest?

 Option A: 2 years

 Option B: 3 years

 Option C: 1 year

 Option D: 4 years

 Option E: 5 years
answer:
Option A


question:
Question: The probability of a team winning a match given Matt is playing the match is 0.70. The probability of the team winning a match given Matt is not playing the match is 0.5. The probability of Matt playing any match is 0.8.
If it is known that the team has won the last match, what is the probability that Matt played the match?

 Option A: 0.8321

 Option B: 0.8484

 Option C: 0.8571

 Option D: 0.7531

 Option E: 0.8213
answer:

Option B