Three cars participate in a race. The probability that any one of them has an accident is 0.1. Find the probability that all the cars reach the finishing line without any accident.

In the items produced by a factory, there are 10% defective items. A sample of 6 items is randomly chosen. Find the probability that this sample contains.

(i) exactly 2 defective items

(ii) not more than 2 defective items

(iii) at least 3 defective items

Assume that on an average one telephone number out of 15, called between 3 p.m. on weekdays, will be busy. What is the probability that if six randomly selected telephone numbers are called, at least 3 of them will be busy?

Past records show that 80% of the operations performed by a certain doctor were successful. If the doctor performs 4 operations in a day, what is the probability that at least 3 operations will be successful?

The probability of a man hitting a target is (1/4). If he fires 7 times, what is the probability of his hitting the target at least twice?