A group of 10 boys are randomly divided in to two teams containing 5 boys each. The probability that the two tallest boys in different team is
Three numbers are to be selected from the set of the first 15 natural numbers so that all the selected are consecutive or none of them are consecutive. The probability of selecting them is
The marks of some students were listed out of 75. The SD of marks was found to be 9. Subsequently the marks were raised to a maximum of 100 and variance of new marks was calculated. The new variance is
81
122
144
None of these
The mean and variance of a binomial distribution are 4 and 3 respectively, then the probability of getting exactly six
successes in this distribution is
A and B stand in ring along with 10 other persons. If the arrangement is at random, the probability, that there are
exactly 3 person between A and B, is
There are 2 teams with n persons in each; The probability of selecting 2 persons from one team and 1 person from the other team is 6/7 then n is equal to
3
4
5
6
A key bunch contains 10 keys of which only one key can open a door. A man tries to open the door by choosing a
key at random and discarding the wrong key after each trial. The probability that the door is opened in the fifth trial is
Out of 13 group application for a job, there are 5 women and 8 men. It is desired to select to persons for the job. The
probability that at least one of the selected persons will be a women is
Three houses are available in a locality. Three persons apply for the houses. Each applies for one house without consulting others. The probability that all the three apply for the same house, is
If in a frequency distribution the mean and median are 21 and 22 respectively, then its mode is approximately
24.0
25.5
20.5
22.0
