Answer:
<h3>
</h3>
Step-by-step explanation:
?
Now, Using Pythagoras theorem
plug the values
⇒
Evaluate the power
⇒
Swap the sides of the equation
⇒
Move constant to right hand side and change it's sign
⇒
Calculate the difference
⇒
Squaring on both sides
⇒
Hope I helped!
Best regards!
The question is incomplete! Complete question along with answer and step by step explanation is provided below.
Question:
The lifetime (in hours) of a 60-watt light bulb is a random variable that has a Normal distribution with σ = 30 hours. A random sample of 25 bulbs put on test produced a sample mean lifetime of = 1038 hours.
If in the study of the lifetime of 60-watt light bulbs it was desired to have a margin of error no larger than 6 hours with 99% confidence, how many randomly selected 60-watt light bulbs should be tested to achieve this result?
Given Information:
standard deviation = σ = 30 hours
confidence level = 99%
Margin of error = 6 hours
Required Information:
sample size = n = ?
Answer:
sample size = n ≈ 165
Step-by-step explanation:
We know that margin of error is given by
Margin of error = z*(σ/√n)
Where z is the corresponding confidence level score, σ is the standard deviation and n is the sample size
√n = z*σ/Margin of error
squaring both sides
n = (z*σ/Margin of error)²
For 99% confidence level the z-score is 2.576
n = (2.576*30/6)²
n = 164.73
since number of bulbs cannot be in fraction so rounding off yields
n ≈ 165
Therefore, a sample size of 165 bulbs is needed to ensure a margin of error not greater than 6 hours.
Answer:
1/4
Step-by-step explanation:
1/4 x 2 = 1/2
1/2 divided by 2 is 1/4
Add up the fractional amounts and divide them by however many amounts there are..........
eg.
Step 1:Add the fractions
1/6 + 5/8 +3/4
(find the LCD)
1/6 + 5/8 + 3/4 = 4/24 + 15/24 + 18/24 = 37/24
Step 2: Divide the sum by the number of numbers in the set
37/24 ÷ 3= 37/24 ÷ 3/1= 37/24 X 1/3= 37/72
<span>So the mean (average) is 37/72</span>
