Question

Question 8 of 10 (1 point) Attempt 1 of Unlimited | View question in a popup 11.3 Section Exercise 11 (critical value, table) Strength of concrete: The compressive strength, in kilopascals, was measured for concrete blocks from five different batches of concrete, both three and six days after pouring. The data are as follows. Can you conclude that the mean strength after three days is greater than the mean strength after six days? Let un represent the mean strength after three days and 4d = ui-42. Use the a=0.10 level and the critical value method with the table. Block 1 2. 3 4 5 After 3 days 1370 1326 1380 1389 1358 After 6 days 1325 1305 1332 1318 1375 ol. Send data to Excel Part 1 of 5 (a) State the null and alternate hypotheses. Hud = 0

Answer 1

	After 3 Days	After 6 Days	d	d-d¯	(d-d¯)²
	1370	1325	45	11.4	129.96
	1326	1305	21	-12.6	158.76
	1380	1332	48	14.4	207.36
	1389	1318	71	37.4	1398.76
	1358	1375	-17	-50.6	2560.36
Total			168		∑(d-d¯)²=4455.2
Mean(d¯)			168/5=33.6

$\\ Mean(\bar{d})=33.6\\\\ Standard~deviation(s)=\sqrt{\frac{\sum (d-\bar{d})^2}{n-1}}=\sqrt{\frac{4455.2}{4}}=33.37$

a.)Ho : Hd=0 H:Hd > 0 2.)Critical Value(ta) = 1.533 (use excel function := =T.INV(0.1, 4) d 33.6 3.) Test Statistic(t) 2.25 s/n 33.37/V5 4.) As Test Statistic is greater than critical value, Reject null hypothesis.

5.)There is enough evidence to support the claim that the difference is greater than zero