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.
frankly yes, because when you want inverse a function you must inverse it with line x=y
so when you inverse a function Df and Rf will convert together!
Answer:
-4ctv² + 10xyz - 9
Step-by-step explanation:
(2 + 5xyz - 6tv²c) - (11 - 5yxz - 2ctv²)
2 + 5xyz - 6tv²c - 11 + 5yxz + 2ctv²
-4ctv² + 10xyz - 9
I hope this helps!
Answer:
Step-by-step explanation:
<u>Given polynomial:</u>
- x¹⁹ + x¹⁷ + x¹³ + x⁷ + x⁵ + x³
<u>Group as follows:</u>
- (x¹⁹ + x¹⁷) + (x¹³ + x¹¹) + (x⁷ + x⁵) + (x³ + x) - x =
- x¹⁷(x² + 1) + x¹¹(x² + 1) + x¹⁵(x² + 1) + x(x² + 1) - x
As we see all terms have (x² + 1) as factor apart from the last one.
It means the remainder is - x
Correct choice is C
