Biologists studying the healing skin wounds measured the rate at which new cells closed a razor cut made in the skin of an anesthetized newt. Here are data from 18 newts measured in micrometers (millionths of a meter)per hour:29,27,34,40,22,28,14,35,26,35,12,30,23,18,11,22,23,33.
Questions:
Scientists usually assume that animal subjects are SRSs from their species or genetic type. Treat these newts as an SRS and suppose you know that the standard deviation of helaing rates for this species of newts is 8 mincrometers per hour. Give 90% confidence interval for mean healing rate for the species.

same question different time. I've since learned about stem and leaf plots.
Split the digits into 10's place and ones place and type the data into an orderly fashion.
The Tens are the 'stem' and the leaves are the ones place.. It gives a histogram in text form.
1 4281
2 97286323
3 45503
4 0

Spliting the stem could spread out the data so that each ten's place could have a high and low secti0n 0-4 and 5-9
1L421
1H8
2L233
2H9786
3L403
3H55
4L0
4H

for your 2nd part the 90% confidence level range is equal
Average +/- [Std dev / square root (n-1)]* t

Range= 25.7 +/- [8 /(sqrt (18-1)]*1.33

I'd mistakenly given 95% confidence t score before

25.7+/- 2.6 microns/hr