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: The ratio between the speeds of two trains is 7 : 8. If the second train runs 400 kms in 4 hours, then the speed of the first train is:

 Option A: 70 km/hr

 Option B: 75 km/hr

 Option C: 84 km/hr

 Option D: 87.5 km/hr

 Option E: 88.5 km/hr
[A]: Option D


[Q]: Question: A library has an average of 1000 visitors on Sundays and 700 on other days. The average number of visitors per day in a month of 30 days beginning with a Sunday is :

 Option A: 740

 Option B: 750

 Option C: 760

 Option D: 770

 Option E: 775
[A]: Option B


[Q]: Question: What is the square root of 0.16

 Option A: 0.4

 Option B: 0.04

 Option C: 0.004

 Option D: 4

 Option E: 1
[A]:
Option A