3. Incorrect. The answer is false not true. To calculate the value of 'a', we have to calculate the definite integral of the density function between 0 and 1. Remember that the the value of the integral of a density function over its domain is equal to 1:

1 = a [1/2 - 1/3] => a = 6

The graph of this 'oil discovery function' (which is in fact a probabilistic density function) is: