The chance of defective screws in three boxes `A ,B ,Ca r e1//5,1//6,1//7,` respectively. A box is selected at random and a screw draw in from it at random is found to be defective. Then find the probability that it came from box `Adot`

There are N + 1 identical boxes each containing N wall clocks. r^(th) box contains (r - 1) defective and (N-r+1) effective clocks for 1lerleN+1. A box is selected at random and from this box a clock is chosen at random and is found to be effective, the probability that it is from km box is (2N – 2 k +lambda)/(N^2+N) then find lambda.

In a bolt factory three machines A ,B and C manufacture 25% , 35% and 40% of the total production respectively. Of their respective outputs, 5% , 4% and 2% are defective. A bolt is drawn at random from the total production and it is found to be defective. Find the probability that it was manufactured by machine C.

A box contains 3 coins B_(1), B_(2),B_(3) and the probability of getting heads on the coins are (1)/(2), (1)/(4),(1)/(8) respectively. If one of the coins is selected at random and tossed for 3 times and exactly 3 times and exactly 3 heads appeared, then the probability that it was coin B_(1) is

In a factory which manufactures bolts, machines A. B and C manufacture respectively 25%, 35% and 40% of the bolts. Of their outputs, 5, 4 and 2 percent are respectively defective bolts. A bolt is drawn at random from the product and is found to be defective. What is the probability that it is manufactured by the machine B?

A box contains 90 discs, numbered from 1 to 90. If one disc is drawn at random from the box,find the probability that it bears a prime number < 23.

For k=1,2,3 the box B_k contains k red balls and (k+1) white balls. Let P(B_1)=1/2,P(B_2)=1/3 and P(B_3)=1/6 .A box is selected at random and a ball is drawn from it. If a red ball is drawn, then the probability that it has come from box B_2 , is

A box contains 7 red balls, 8 green balls and 5 white balls. A ball is drawn at random from the box. Find the probability that the ball is white.

Suppose we have four boxes A,B,C and D containing coloured marbles as given below :One of the boxes has been selected at random and a single marble is drawn from it. If the marble is red, what is the probability that it was drawn from box A? box B?, box C?

Box-1 contains 30 cards marked from 1 to 30 and Box-2 contains 20 cards marked from 31 to 50. A box is selected and a card is drawn. If the number on the card is non-prime then what is the probability that it came from Box 1.

Three electric bulbs are chosen at random from 15 bulbs of which 5 are defective. The probability that atleast one is defective is