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Answer:

Step-by-step explanation:
Since the sample size is quite large, we can use the z-distribution.
The margin of error is given by

Where n is the sample size, s is the sample standard deviation and
is the z-score corresponding to a 90% confidence level.
The z-score corresponding to a 90% confidence level is
Significance level = α = 1 - 0.90= 0.10/2 = 0.05
From the z-table at α = 0.05
z-score = 1.645

Therefore, the margin of error is 0.776.
Answer:
0.1*√20000 = 14.1421356237
-0.05*√28800 = -8.48528137424
Step-by-step explanation:
Answer: Yes, Yukio is correct.
Step-by-step explanation:
Assuming that Triangle DEF and ABC have the same angles (they do because they are right-angled), we can take the length from the larger triangle (DEF) and divide it by the length of the smaller triangle (ABC).
Length of DEF = 6cm
Length of ABC = 2cm
= 6/2
= 3
Proves that scale of DEF to ABC is 3:1
Answer:
Step-by-step explanation:
The volume for a sphere is
. Our radius is 21 inches, so
and
. Multiplying straight across the top, using the fact that 3.14 is pi:
and divide to get that
V = 38772.72 in^3