Answer:
A sample size of 385 is needed.
Step-by-step explanation:
We have that to find our 
level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of 
.
That is z with a pvalue of 
, so Z = 1.96.
Now, find the margin of error M as such
In which 
is the standard deviation of the population and n is the size of the sample.
You feel that a reasonable estimate of the standard deviation is 10.0 hours.
This means that 
What sample size is needed so that the expected margin of error of your estimate is not larger than one hour for 95% confidence?
A sample size of n is needed. n is found when M = 1. So
Rounding up:
A sample size of 385 is needed.
Original height of tree = (x+5) m
In triangle ABC x square = 5 square + 12 square
X square = 25+144
X square = 169
X = 13
Thus the original height of the tree was 13+15 = 18m
Answer:
160miles
Step-by-step explanation:
400miles uses15g what about 6g.
Using cross multiplication. Multiply 6x400/15 = 160miles
A=base*height*1/2 OR A=base*height/2
A=8*7/2
A=28
Answer:
Step 2.
Step-by-step explanation:
When you have a coefficient on a side of the equation that you need to get rid of, you must divide by the number. For example, in the problem:
3(x+8)² = 75
Here, you need to divide both sides by '3' instead of multiplying, which was done instead. Then you get:
(x+8)² = 25.
Therefore, his mistake was made at Step 2.
