Question 5.21: A sample of 10 concrete blocks manufactured by a certain pro...

For a 95% prediction interval, α = 0.025. We have a sample size of n = 10,so we consult the Student’s t table (Table A.3) to find t_{9, .025} = 2.262. Using expression (5.19) with \bar{X}=1312 and s = 25, the 95% prediction interval is 1312 \pm 2.262(25) \sqrt{1+1 / 10}, or (1253, 1371).

\bar{X}\pm t_{n-1, \alpha / 2^{S}}{}\sqrt{1+\frac{1}{n}}        (5.19)