i got 20/24 on my

i got 20/24 on my first statistics quiz. 83%. i missed two out of 12 questions. for those of you who had statistics, can you tell me how to get the answer on the two i got wrong?

1. The variance of 10 measurements of people’s height (in inches) is computed to be 25. The standard deviation of these measurements is (5, 2.5, .5, or 250)

2. A soft-drink machine can be regulated so that it discharges an average of x ounces per cup. If the ounces of fill are normally distributed with a standard deviation of 0.4 ounces, what value should x be set at so that 6-ounce cups will overflow only 2% of the time? (6.82, 6, 5.18, or 5.6)
the x is actually that symbol that looks like a u with a long left side.

i would really appreciate any help. i thought i knew how to do those, but apparently i don’t. i want to know how to do them in case anything similar shows up on the first test.