Answer:
0.68269
Step-by-step explanation:
When we are to find the z score for population where a random sample is picked, the z.score formula we use is
z = (x-μ)/Standard error, where
x is the raw score,
μ is the population mean
Standard error = σ/√n
σ is the population standard deviation
n = random number of samples
For : x = 38 minutes, μ = 40, σ = 10, n = 5
z = 38 - 40/10 /√25
= -2/10/5
= -2/2
= -1
Determining the probability value using z table
P(x = 38) = P(z = -1)
= 0.15866
For : x = 42 minutes, μ = 40, σ = 10, n = 25
z = 42 - 40/10 /√25
= 2/10/5
= 2/2
= 1
Determining the probability value using z table
P(x = 42) = P(z = 1)
= 0.84134
The probability that their average waiting time will be between 38 and 42 minutes is calculated as
P(-Z<x<Z)
= P(-1 < x < 1)
= P(z = 1) - P(z = -1)
= 0.84134 - 0.15866
= 0.68269
Therefore, the probability that their average waiting time will be between 38 and 42 minutes is 0.68269
Answer:
Ivy is 6 years old and Rose is 12 years old.
Step-by-step explanation:
To solve this problem, two variables are necessary since we have two unknown variables: Ivy's age and Rose's age.
Ivy's age will be 
and Rose's age will be 
"Ivy is half as old as her sister":
this will be our <u>fist equation.</u>
"In six years, Ivy will be two-thirds as old as Rose"
in six years Ivy will have 
years, and Rose will have 
years, so for this sentence we have the equation:
this will be our <u>second equation.</u>
Substituting the value of x from the first equation into the second, and solving for y(Rose):
Rose is 12 years old.
and Ivy (using the fist equation):
Ivy is 6 years old.
Answer: C -1
calculate it from i and imaginary numbers
13) 120 + 1.5 + 0.25 = 121.75 pounds
14) 4 - 1.5 = 2.5 pints
15) (2.25)(32)= $72
Answer:
y = - 49
Step-by-step explanation:
Given
7x - 2y = 35 ← substitute x = - 9 into the equation
7(- 9) - 2y = 35, that is
- 63 - 2y = 35 ( add 63 to both sides )
- 2y = 98 ( divide both sides by - 2 )
y = - 49
