Need with three will give 25 points

How much dextrose 70% must be mixed with dextrose 5% to prepare 1,000 ml of dextrose 20%?

2people are trying different phones to see which one has the better talk time. chatlong has an average of 18 hours with a standard deviation of 2 hours and talk-a-lot has an average of 20 hours with a standard deviation of 3. the two people who tested their phones both got 20 hours of use on their phones. for the z-scores i got 1 for the chatlong company and 0 for talk-a-lot. what is the percentile for each z-score?

Let f(x) = 5/x and g(x)=2x2+5x. what two numbers are not in the domain of f o g