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:
The Hypotenuse is side just opposite to the right angle.
Step-by-step explanation:
By Pythagoras' theorem,
c^2=a^2+b^2
c^2(hypotenuse to be found)= 30^2+ 16^2
<em>c^2=1156
</em>
<em><u>Therefore, c ( i.e. the hypotenuse) will be the square root of 1156. </u></em>
<em><u>The square root of 1156 is 34. </u></em>
<h2><em><u>
Thus, c ( hypotenuse) = 34</u></em></h2>
Hope it helped :)
Answer:
volume of a cube = 441cm3.
l³=441cm³
l=7.6cm
Answer:
(Choice A) A The 1 Seed
Step-by-step explanation:
The computation is shown below:
The highest rate of apple per tree is
For Seed
= 38,614 ÷ 84 = 460 approx
For Sweet and sour
= 75509 ÷ 178 = 424 approx
And, for apple valley
= 135220 ÷ 3212
= 433 approx
As it can be seen that the highest rate per of apple per tree is of seed i.e. 460 approx
hence, the correct option is choice A
Answer: x2= 6
FYI: The x2 is x squared
Step-by-step explanation:
Simplifying
4x2 + 7 = 31
Reorder the terms:
7 + 4x2 = 31
Solving
7 + 4x2 = 31
Solving for variable 'x'.
Move all terms containing x to the left, all other terms to the right.
Add '-7' to each side of the equation.
7 + -7 + 4x2 = 31 + -7
Combine like terms: 7 + -7 = 0
0 + 4x2 = 31 + -7
4x2 = 31 + -7
Combine like terms: 31 + -7 = 24
4x2 = 24
Divide each side by '4'.
x2 = 6
Simplifying
x2 = 6
