In this task, you need to provide the correct option for a given problem from the provided options.

[EX Q]: Problem: the ratio of the arithmetic mean of two numbers to one of the numbers is 5 : 9 . what is the ratio of the smaller number to the larger number ? 
Options: a ) 1 : 5 , b ) 1 : 6 , c ) 1 : 7 , d ) 1 : 8 , e ) 1 : 9
[EX A]: e

[EX Q]: Problem: the ratio of number of boys and girls in a school is 2 : 5 . if there are 420 students in the school , find the number of girls in the school ? 
Options: a ) 150 , b ) 250 , c ) 300 , d ) 370 , e ) 280
[EX A]: c

[EX Q]: Problem: in what ratio must tea at rs . 60 per kg be mixed with tea at rs . 70 per kg so that the mixture must be worth rs . 63 per kg ? 
Options: a ) 3 : 1 , b ) 3 : 2 , c ) 4 : 3 , d ) 7 : 3 , e ) none
[EX A]:
d