st(1) doesn't tell if he answered all questions in test, Insuff
st(2) Suff as it precisely states ratio and no if correct and incorrect questions

b

kishokbabu wrote:John took a test that had 60 qns numbered from 1 to 60. How many of the qns did he answer correctly?

a) The no of the qns he answered correctly in the first half of the test was 7 more than the no he answered correctly in the second half of the test.
b) He answered 5/6 of the odd numbered qns correctly and 4/5 of the even numbered questions correctly.

John took a test that had 60 qns numbered from 1 to 60. How many of the qns did he answer correctly?

a)The no of the qns he answered correctly in the first half of the test was 7 more than the no he answered correctly in the second half of the test.

let x be the number of questions answered correctly in the second half of the test, then x+7 is the number of questions answered correctly in the first half of the test. total number of questions answered correctly = 2x + 7. As we do not know the value of x, this statement is insufficient to answer the question

b)He answered 5/6 of the odd numbered qns correctly and 4/5 of the even numbered questions correctly.

Number of even numbered questions : 30
Number of odd numbered questions : 30
Number of even numbered questions answered correctly: (4/5)*30 = 24
Number of odd numbered questions answered correctly: (5/6)*30 = 25
Total number of questions answered correctly:49
Sufficient to answer the question

Answer :B

p.s: You need not solve for the values but the illustration above is for the benefit of fellow BTGers who are not comfortable solving DS problems.