A company has two plants to manufacture scooters. Plant-1 manufactures 70 of the scooters and plant-2 manufactures 30%. At plant-1, 30% of the scooters are rated of standard quality and at plant-2, 90% of the scooters are rated as standard quality. A scooter is chosen at random and is found to be of standard quality. What is the total probability of choosing a scooter of standard model and of premium model.
a) 1/2
b) 1/4
c) 3/4
d) 1