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.

[Q]: 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
[A]: Option B


[Q]: Question: The parameter of a square is equal to the perimeter of a rectangle of length 16 cm and breadth 14 cm. Find the circumference of a semicircle whose diameter is equal to the side of the square. (Round off your answer to two decimal places)

 Option A: 77.14 cm

 Option B: 47.14 cm

 Option C: 84.92 cm

 Option D: 94.94 cm

 Option E: 23.57 cm
[A]: Option E


[Q]: Question: It is required to fix a pipe such that water flowing through it at a speed of 7 metres per minute fills a tank of capacity 880 cubic metres in 10 minutes. The inner radius of the pipe should be :

 Option A: √2 m

 Option B: 2 m

 Option C: 1⁄2 m

 Option D: 1⁄√2 m

 Option E: None of these
[A]:
Option B