Two identical ball bearings Pand Q are operating at loads

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Two identical ball bearings Pand Q are operating at loads 30 kN and 45 kN respectively. The ratio of the life of bearing P to the life of bearing Q is

1. 81/16
2. 27/8
3. 9/4
4. 3/2

Correct Option: B

For ball bearing
P.(L)^1/₃ = C
Given: P_P = 30 kN
P₂ = 45 kN

L_P	=		P₂		³
L₂			P_P

	45		³	=		3		³	=	27
	30					2				8