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.
Answer:
$0.60
step-by-step explanation:
4.85 + 1.55 = 6.40
7.00 - 6.40 = 0.60
Answer: Nick must now at least 6 yards.
Step-by-step explanation:
Since Nick has $80 saved already, and he makes $40 per yard that he mows, thus can be put up in an equation as:
= 80 + 40y
where y = number of yards
Since Nick needs to raise at least $320 for his trip, the equation to solve this will be:
80 + 40x ≥ 320
40x ≥ 320 - 80
40x ≥ 240
x ≥ 240/40
x ≥ 6
Therefore, Nick must now at least 6 yards.
Answer:
69
Step-by-step explanation:
so x2 will give you 9 times 7 which is 63. add it to 2 times 3 which is 63 + 6 will give you 69.