If the 5 scores have a mean of 8, then their total sum would be 8*5 = 40
Now if one score if added (let's call this score x), there are 6 scores and the mean changes to 9, thus:
(40 + x)/6 = 9
40 + x = 54
x = 14
Answer:
A) $15
Step-by-step explanation:
let x represent the regular price of the mirror
so, 20% of x = 3
20/100 * x = 3
20x = 300
x = 300/20
x = 15
Hence, the regular price of the mirror is $15
Answer: The equation parallel to the line is y=3x+8
Step-by-step explanation: Parallel lines have the same gradients, wr have a gradient for the above line which 3. The standard formula for the linear equation is y=mx+c
We have to calculate c since we have x and y.
y=mx+c
5= 3(-1)+c
c=8
The equation become y=3x+8
Answer : 0.0129
Step-by-step explanation:
Given : Based on FAA estimates the average age of the fleets of the 10 largest U.S. commercial passenger carriers is
years and standard deviation is
years.
Sample size : 
Let X be the random variable that represents the age of fleets.
We assume that the ages of the fleets of the 10 largest U.S. commercial passenger carriers are normally distributed.
For z-score,

For x=14

By using the standard normal distribution table , the probability that the average age of these 40 airplanes is at least 14 years old will be :-

Hence, the required probability = 0.0129