Answer: 25
Explains:
Use: a^2+ b^2= c^2
1. The fractions shown are 3/4 and 6/8.
2. The multiplier is 2.
3. The fractions shown are 12/18 and 4/6
4. The divisor is 3.
Answer:
The y-intercept represents the flat fee.
Step-by-step explanation:
The y-intercept on the graph would be the point at which the line cuts across or intercepts the y-axis. At this point, the value of x (miles travelled) would be 0. The y-intercept in this case, would be the flat fee which is given as $2.
At x = 0, f(0) = 2.
The y-intercept represents the flat fee on the graph of f(x).
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.
