Sol. Let’s assume,
Bob – x chocolates
Alice – 5x/4 chocolates (25% more than Bob)
Difference between the number of chocolates they have = x/4
St. (1) Together Alice and Bob have less than 30 but more than 20 chocolates.
20< 5x/4+x<30
20< 9x/4<30
80< 9x<120
Possible values for x = 9, 10, 11, 12
Since value of x must be divisible by 4 as x/4 is integer, only 12 satisfy the condition and hence difference between number of chocolates they have = 3
Statement (1) is sufficient. BCE eliminated
St. (2) Difference between the squares of number of chocolates with Alice and Bob is 27 times the difference between the number of chocolates with Alice and Bob.
(5x/4)^2-(x)^2=27 (x/4)
25x/16-x=27
Above equations can be solved and hence sufficient to find the value of x.
Hence statement (2) is also sufficient. “A” eliminated and correct answer is D.