HELP HAVING BAD DAY During a certain day, a worker did 77 parts. He usually does 55 parts per day. What was the percent by which he increased the usual number of parts?

With #! i’ve tried to figure it out but i can’t.

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?

I'm confused on this could anyone me and show me what i need to do to solve it.