Can someone explain to me how to solve problems like this without a number instead of a variable? Thanks!

Suppose you want just guess at the answers in a 5 question multiple-choice test. each question has 3 responses and only one is correct. what is the probability of getting two questions right just guessing? 20 points 0.3275 0.2753 0.7532 none of the above

Using two or more complete sentences, describe how you can find a vector parallel to b=-2,3

Suppose a laboratory has a 30 g sample of polonium-210. the half-life of polonium-210 is about 138 days how many half-lives of polonium-210 occur in 1104 days? how much polonium is in the sample 1104 days later? 9; 0.06 g 8; 0.12 g 8; 2,070 g