RRB Government Jobs Exams Category

An urn contains three white and four black balls. One of the balls is drawn out of the urn. Find the probability that the ball is white.

Read Solution (Total 2)

Ans 3/7
3C1/7C1
9 years agoHelpfull: Yes(0) No(0)

total no of balls=7
no of ways of on ball is drwan from 7=7c1=7
no of ways that ball is white=3c1=3
ans =3/7
9 years agoHelpfull: Yes(0) No(0)

RRB Other Question

An urn contains three white and four black balls. We take out a ball and put it in a drawer without looking at it. After that we take out a second ball. Find the probability that this ball is white. You wish to temporarily mount a wire to serve as the antenna of your transmitter in your laboratory. It is necessary that this be straight and as long as possible. You recall that when you had the floor covered required exactly 200 square yards of carpet and that the long side of the room was 20 yards. You also know that the height of the room is 12 feet. You go to the store room to get the wire but find that it can only be supplied in lengths that are an integral multiple of 1 meter. What length of wire do you take back to the lab?