For the following questions answer them individually
If the mean of the following distribution is 50. then the ratio of the missing frequencies $$f_1$$ and $$f_2$$ is
The mode of the following distribution of marks obtained by a group of students is approximately
The mean of the numbers a, b, 8, 5, 10 is 6 and their variance is 6.80. Then the difference between a and b is
The rank correlation coefficient between two characteristics X and Y of a group is found to be 0.9. If the sum of the squares of the differences in their ranks is given to be 56, then the number of individuals in that group is
The probability that a flight arrives on time is 0.7 and the probability that a flight departs on time is 0.8. The probability that a flight neither arrives on time nor departs on time is 0.15. Then the probability that flight arrives on time and departs on time is
Bag B1 contains 4 white and 2 black balls. Bag B2 contains 3 white and 4 black balls. A bag is drawn at random and a ball is chosen at random from it. Then the probability that the ball drawn is white, is
In a construction company the probability that the workers go on strike is 0.65 and the probability that a construction job will be completed on time if there is no strike is 0.80. If the probability that the construction job is completed on time even if there is strike is
0.32, then the probability that the construction job is completed on time is
A bag contains 4 red and 5 black balls. Another bag contains 3 red and 6 black balls. One ball is drawn from the first bag and two balls are drawn from the second bag at random. The probability that out of the three balls. two are black and one is red is