$I$ toss three coins together. The possible outcomes are no heads,$1$ head,$2$ heads and $3$ heads. So,$I$ say that probability of no heads is $\frac{1}{4}$. What is wrong with this conclusion?

There are $6$ green,$5$ red,and $4$ blue identical balls in a bag. One ball is drawn at random from the bag. The probability that the ball drawn is not red is ...........

Box $A$ contains $25$ slips of which $19$ are marked $Rs. 1$ and others are marked $Rs. 5$ each. Box $B$ contains $50$ slips of which $45$ are marked $Rs. 1$ each and others are marked $Rs. 13$ each. Slips of both boxes are poured into a third box and reshuffled. $A$ slip is drawn at random. What is the probability that it is marked other than $Rs. 1$?

There are chits numbered $1$ to $20$ in a box. One chit is drawn at random. Find the probability that the number on the chit is a prime number.

Total number of outcomes in the experiment of rolling two balanced dice once is ..........

An unbiased coin is tossed thrice. Then,the number of total outcomes is ............