The tickets in a box are numbered from 1-20 inclusive. if a ticket is chosen at random and replaced, and then a second ticket is drawn at random, what is the probability that the sum of their numbers is even?

7 + 5 = 12 so is an even number that the ticket the choose

First step is to get rid of the square root. remember that a square root is the same as raising to the (1/2) power. see below: multiply exponents per exponent rules to get: remember you subtract exponents from the denominator and add exponents in the numerator so: simplify further: so a is the correct choice. if you don't understand this google exponent rules and it will you understand. look at the image results.