Justin is working two summer jobs, making $8 per hour babysitting and $14 per hour lifeguarding. Last week Justin earned a total
1 answer:
Answer:
Justin worked as a babysitter 8 hours and worked as a lifeguard 2 hours last week
Step-by-step explanation:
Let
x ----> number of hours worked as a babysitter last week
y ----> number of hours worked as a lifeguard last week
we know that
----> equation A
----> equation B
Solve the system by substitution
Substitute equation B in equation A
solve for y
Find the value of x
therefore
Justin worked as a babysitter 8 hours and worked as a lifeguard 2 hours last week
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Answer:
Step-by-step explanation:
A car traveled at a constant speed as shown in the graph.
Distance traveled is on the y-axis and duration of travel on the x-axis.
Point A(3.5, 210) shows,
Distance traveled = 210 miles
Time to travel = 3.5 hours
So the point (3.5, 210) shows the distance traveled by the car in 3.5 hours is 210 miles.
Slope of the line = speed of the car =
=
= 60 mph
Now we will find the speed of the car at another point B(1, 60).
If the speed of car is same as the point B as of point A, point B will lie on the graph.
Speed of the car at B(1, 60) =
=
= 60 mph
Hence, we can say that point B(1, 60) lies on the graph.
notice the picture of the graph added here
low and behold, x = -17, y is 0, and x= 15, y is 0
the graph is touching the x-axis, an x-intercept
or so-called, a "solution"
Answer:
a) P(12.99 ≤ X ≤ 13.01) = 0.3840
b) P(X ≥ 13.01) = 0.3075
Step-by-step explanation:
To solve this question, we need to understand the normal probability distribution and the cental limit theorem.
Normal probability distribution
Problems of normally distributed samples are solved using the z-score formula.
In a set with mean and standard deviation
, the zscore of a measure X is given by:
The Z-score measures how many standard deviations the measure is from the mean. After finding the Z-score, we look at the z-score table and find the p-value associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X. Subtracting 1 by the pvalue, we get the probability that the value of the measure is greater than X.
Central Limit Theorem
The Central Limit Theorem estabilishes that, for a normally distributed random variable X, with mean and standard deviation
, the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean
and standard deviation
.
For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.
In this problem, we have that:
(a) Calculate P(12.99 ≤ X ≤ 13.01) when n = 16.
Here we have
This probability is the pvalue of Z when X = 13.01 subtracted by the pvalue of Z when X = 12.99.
X = 13.01
By the Central Limit Theorem
has a pvalue of 0.6915
X = 12.99
has a pvalue of 0.3075
0.6915 - 0.3075 = 0.3840
P(12.99 ≤ X ≤ 13.01) = 0.3840
(b) How likely is it that the sample mean diameter exceeds 13.01 when n = 25?
P(X ≥ 13.01) =
This is 1 subtracted by the pvalue of Z when X = 13.01. So
has a pvalue of 0.6915
1 - 0.6915 = 0.3075
P(X ≥ 13.01) = 0.3075