For the following questions answer them individually
If the arithmetic mean of the first n natural number is 191 , then the sum of the digits in n is
If the mode and the median of a data are 75 and 69 respectively, then the mean of the data is
If $$x_{1} , x_{2} , ... , x_{20}$$ are observations in a data whose mean is 4 and variance is 9, then
$$\sum_{i=1}^{20}x_{i}(x_{i}+1)$$=
When 3 fair dice are thrown at random, the probability of getting different numbers on them is
If a fair coin is tossed six times, the probability of getting exactly 4 consecutive heads is
If 3 boys and 4 girls sit in a row at random, then the probability that all boys sit together is
If two cards are drawn at random from a well shuffled pack of 52 cards, then the probability that both are not spade cards is