A student determined Young's Modulus of elasticity using the formula $Y = {{Mg{L^3}} \over {4b{d^3}\delta }}$. The value of g is taken to be 9.8 m/s², without any significant error, his observation are as following.

Physical Quantity	Least count of the Equipment used for measurement	Observed value
Mass (M)	1 g	2 kg
Length of bar (L)	1 mm	1 m
Breadth of bar (b)	0.1 mm	4 cm
Thickness of bar (d)	0.01 mm	0.4 cm
Depression ($\delta $)	0.01 mm	5 mm

Then the fractional error in the measurement of Y is :