the difference with T-distribution and normal

Hi, I'm confused, I don't know if I got the t- distribution right, and I can't fiqure out what value to use for the normal distribution table. Could someone please help me.

Construct the indicated confidence interval for the population mean. Using (a) a t-distribution (b) if you had incorrectly used a normal distribution which interval would be wider?

C = 0.95, x ( with the line on top) = 13.4, s= 0.85, n = 8

This is what I got for the t-distribution interval

**3.13.4 +** 2.364, is this even close?

Thank you in advance.