Answer:
Check the explanation
Step-by-step explanation:
Let X denotes steel ball and Y denotes diamond
= 1/9( 50+57+......+51+53)
=530/9
=58.89
= 1/9( 52+ 56+....+ 51+ 56)
=543/9
=60.33
difference = d =(60.33- 58.89)
=1.44
s12 = 1/9( 502+572+......+512+532) -9/8 (58.89)2
=31686/8 - 9/8( 3468.03)
=3960.75 - 3901.53
=59.22
s1 = 7.69
s22 = 1/9( 522+ 562+....+ 512+ 562) -9/8 (60.33)2
=33295/8 - 9/8 (3640.11)
=4161.875 - 4095.12
=66.75
s2 =8.17
sample standard deviation for difference is
s=![\sqrt{[(n1-1)s_1^2+ (n2-1)s_2^2]/(n1+n2-2)}](https://tex.z-dn.net/?f=%5Csqrt%7B%5B%28n1-1%29s_1%5E2%2B%20%28n2-1%29s_2%5E2%5D%2F%28n1%2Bn2-2%29%7D)
= ![\sqrt{[(9-1)*59.22+ (9-1)*66.75]/(9+9-2)}](https://tex.z-dn.net/?f=%5Csqrt%7B%5B%289-1%29%2A59.22%2B%20%289-1%29%2A66.75%5D%2F%289%2B9-2%29%7D)
= 
=7.93
sd = 
=
=7.93* 0.47
=3.74
For 95% confidence level 
=1.96
confidence interval is
=(1.44 - 1.96* 3.75 , 1.44+1.96* 3.75)
=(1.44 - 7.35 , 1.44 + 7.35)
=(-2.31, 8.79)
There is sufficient evidence to conclude that the two indenters produce different hardness readings.
15.5 I believe but don’t hold me to it!
The phrase has two parts:
Five times the sum of a number and eleven, divided by
three times the sum of the number and eight
Let the number be x. Five times the sum of a number and eleven means 5 multiplied to the sum of x and 11. In expression this will be written as:
5(x + 11)Three times the sum of the number and eight means 3 multiplied to the sum of x and 8. In expression this will be written as:
3(x + 8)So, the overall expression will be:
Lord help me hdbdbdbdbfbbfbfbrbbdbdbdbdnrjbdbdbdbdbdbdbhdhrbtbrbdbdbbrrbrgrggrgrhhrhr
Because 0.24 = 24/100 and 1/4= 25/100 and 0.24 = 24/100 and 2/4/ 50/100=2
and so she missed calcuated and so its wrong.
the correct answer is 0.24<2/4 then 0.24=/2/4
wrong symbol
