The question consists of two statements numbered "I and II" given below it. You have to decide whether the data provided in the statements are sufficient to answer the question.
There are three gardens 'X', 'Y' and 'Z'. The average number of trees in 'X', 'Y' and 'Z' is 240. Find the number of trees in 'Y' is how much percent more or less than total number of trees in 'X' and 'Z'.
Statement I: Number of trees in 'Z' is 'a' more than the number of trees in 'X' and the number of trees in 'Y' is 'a' more than that in 'Z'.
Statement II: The difference between number of trees in 'X' and 'Y' is 60.

Let the number of trees in 'X', 'Y' and 'Z' be 'p', 'q' and 'r' respectively.

So, sum of the number of trees in 'X', 'Y' and 'Z' = 240 X 3

So, (p + q + r) = 720

Statement I:

Given, (r - p) = a.......(I)

Or, (q - r) = a..........(II)

From (i) & (ii), We cannot determine the value of 'a'

So, data in statement I alone is not sufficient to answer the question.

Statement II:

Case I:

We have, q = p + 60

Case II:

We have, q = p - 60

But we do not have any other data.

So, data in statement II alone is not sufficient to answer the question.

From Statement I and Statement II:

So, 'r' = 240

So, p + q = 720 - 240 = 480

And q - p = 60

So, q = (480 + 60) /2 = 270

And 'p' = (480 - 60) /2 = 210

So, total number of trees in 'X' and 'Z' = 210 + 240 = 450

Number of trees in 'Y' = 270

So, required percentage = {(450 - 270) /450} X 100 = 40% less

The data in both statements I and II together is necessary to answer the question.