Question

Ex.1

The probability that cars passing a speed camera are speeding is 0.25. If 752 cars pass the camera, how many of the cars would you expect to be speeding and what would be the variance?

a)E(X)=188 and V(X)=141

b)E(X)= 564 and V(X)=141

C) E(x)=141 and V(X)= 188

d)E(X)=141 and V(X)=564

Ex2

Occasionally ,a machine producing steel tools need to be reset. The random variable Y is the number of resettings in a month and is modelled by a poisson distribution. This mean number of resettings needed per month has been found to be 6. The probability that fewer than 3 resettings per month are needed is:

a)0.1512

b)0.8488

C)0.9380

D)0.0620

Answer 1