Answer:
see below and attached
Step-by-step explanation:
To solve a system of quadratic equations:
I have done this (see attached workings) but cannot get any of the solutions you've provided. I have even graphed the two functions, and the points of intersection concur with my workings (see attached graph).
Answer:
a)
90% confidence interval for the mean grading time of all composition papers.
(12.47981 , 13.52019)
b)
Appropriate inequality
The interval is ( 12.47981 < μ < 13.52019)
Step-by-step explanation:
<u><em>Explanation</em></u>:-
a)
Given sample size 'n' = 40
Mean of the sample = 13 minutes
standard deviation = 2 min
level of significance = 0.10 or 90%
90% confidence interval for the mean grading time of all composition papers.
( 13 - 0.52019 , 13 + 0.52019)
(12.47981 , 13.52019)
b)
The interval is ( 12.47981 < μ < 13.52019)