Question

An article presents a comparison of the surface hardness of specimens treated for 40 seconds with constant power with that of specimens treated for 40 seconds with exponentially increasing power. Fifteen specimens were treated with each method. Those treated with constant power had an average surface hardness (in N/mm2) of 400.9 with a standard deviation of 10.6. Those treated with an exponentially increasing power had an average surface hardness of 367.2 with a standard deviation of 6.1.

Find a 98% confidence interval for the difference in mean hardness between specimens treated by the two methods

Answer 1

Saleolico intervall for Here we have to find 98% confidence the difference in mean CI=(4,-) + telah menerima Given that X = 400.9 Az = 3672 = 106 $. = 6.1 n = 15 H₂ = 15 C. I = (600.8 -360 2) + de les per a la 013 (33.1) de 57.491 + 2,487 daca to. om, foi tho -2)) 16.01, 28) tal = 2.467 Now, CI= 33.7 & (2.467) 29.972 = 33.7 2 (2.467) (3. 1578)

= 33.7+ 7,79 ها به , ۹۱، ک) -