2. The data set (Concrete1.xlsx) contains the compressivestrength, in thousands of pounds per square inch (psi), of 30samples of concrete taken two and seven days after pouring.(You need to use The Paired Difference Test).
(a) At the 0.10 level of significance, is there evidence of adifference in the mean strengths at two days and at seven days?
(b) Find the p-value in (a) and interpret its meaning.
(c) At the 0.10 level of significance, is there evidence thatthe mean strength is lower at two days than at seven days?
(d) Find the p-value in (c) and interpret its meaning.
| Sample | Two Days | Seven Days |
| 1 | 2.830 | 3.505 |
| 2 | 3.295 | 3.430 |
| 3 | 2.710 | 3.670 |
| 4 | 2.855 | 3.355 |
| 5 | 2.980 | 3.985 |
| 6 | 3.065 | 3.630 |
| 7 | 3.765 | 4.570 |
| 8 | 3.265 | 3.700 |
| 9 | 3.170 | 3.660 |
| 10 | 2.895 | 3.250 |
| 11 | 2.630 | 2.850 |
| 12 | 2.830 | 3.340 |
| 13 | 2.935 | 3.630 |
| 14 | 3.115 | 3.675 |
| 15 | 2.985 | 3.475 |
| 16 | 3.135 | 3.605 |
| 17 | 2.750 | 3.250 |
| 18 | 3.205 | 3.540 |
| 19 | 3.000 | 4.005 |
| 20 | 3.035 | 3.595 |
| 21 | 1.635 | 2.275 |
| 22 | 2.270 | 3.910 |
| 23 | 2.895 | 2.915 |
| 24 | 2.845 | 4.530 |
| 25 | 2.205 | 2.280 |
| 26 | 3.590 | 3.915 |
| 27 | 3.080 | 3.140 |
| 28 | 3.335 | 3.580 |
| 29 | 3.800 | 4.070 |
| 30 | 2.680 | 3.805 |
