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gulaghasi [49]
3 years ago
13

To determine whether they need to hire extra help for the holiday season, the managers of a railroad company want to estimate ho

w long, on average, it takes a crew to unload a freight car at the Lafayette station. They will calculate an estimator as the sample mean of a random sample of unloading times. The managers want the sample mean to have a standard error of 1.51.5 minutes. The corporate office has provided a standard deviation of 99 minutes to use for calculation purposes. How large should the random sample be to ensure the sample mean has the desired standard error?
Mathematics
1 answer:
nadezda [96]3 years ago
3 0

Answer:

36

Step-by-step explanation:

Data provided in the question:

Standard error = 1.5 minutes             ( ∵ number are repetitive 1.51.5 )  

Standard deviation = 9 minutes        ( ∵ number are repetitive 99 )

Now,

Standard error = ( Standard deviation ) ÷ √n

Here,

n is the sample size

Therefore,

on substituting the respective values, we get

1.5 = 9 ÷ √n

or

√n = 9 ÷ 1.5

or

√n = 6

or

n = 6² = 36

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dale is driving to Miami. suppose that the distance (in miles) is a linear function of his total driving time (in minutes). dale
nexus9112 [7]
Considering there is a function (relationship) and that it is linear, the distance will change proportionally to time constantly. In other words, we are taking the speed to be constant throughout the journey.
If we let:
t = time (min's) driving
d = distance (miles) from destination
Then we can represent the above information as:
t = 40: d = 59
t = 52: d = 50
If we think of this as a graph, we can think of the x-axis representing time and the y-axis representing the distance to the destination. Being linear, the function will be a line, i.e. it will have a constant gradient. If you were plot the two points inferred from the information and connect the two dots, you will get a declining line (one with a negative gradient) representing the inversely proportional relationship or equally, the negative correlation between the time driving and the distance to the destination. The equation of this line will be the linear function that relates time and the distance to the destination. To find this linear function, we do as follows:

Find the gradient (m) of the line:
m = Δy/Δx
In this case, the x-values are t-values and our y-values are d-values, so:
Δy = Δd
= 50 - 59
= -9
Δx = Δt
= 52 - 40
= 12
m = -9/12 = -3/4
Note: m is equivalent to speed with units: d/t

Use formula to find function and rearrange to give it in the desired format:
y - y₁ = m(x - x₁)
d - 50 = -3/4(t - 52)
4d - 200 = -3t + 156
4d + 3t - 356 = 0

Let t = 70 to find d at the time:
4d + 3(70) - 356 = 0
4d + 210 - 356 = 0
4d - 146 = 0
4d = 146
d = 73/2 = 36.5 miles

So after 70 min's of driving, Dale will be 36.5 miles from his destination.
3 0
3 years ago
How long would the string be in meters if it is 120 centimeters
nexus9112 [7]
1 meter = 100 centimeters, so 120 centimeters equal to 1.2 meters.
4 0
3 years ago
cylindrical vase holds 8,038.4 cubic centimeters of water. The height of the vase is 40 centimeters. What is the length of the r
iragen [17]

The radius of the cylindrical vase is 8 centimeters, if the cylindrical vase holds 8,038.4 cubic centimeters of water and the height of the vase is 40 centimeters.

Step-by-step explanation:

The given is,

                 Volume of cylindrical vase = 8038.4 cubic centimeters

                 Height of the cylindrical vase = 40 centimeters

Step:1

                Formula for volume of cylindrical vase,

                                     Volume, V=\pi r^{2} h......................(1)

               Where, r - Radius of cylindrical vase

                           h - Height of cylindrical vase  

                From the given,

                                      V = 8038.4 cubic centimeters

                                      h = 40  centimeters  

                Equation (1) becomes,

                             8038.4 = \pi r^{2}  40

                                          =(3.14)(40)r^{2}                               (∵ \pi = 3.14 )

                               8038.4 = 125.6 r^{2}

                                      r^{2} = \frac{8038.4}{125.6}            

                                       r =\sqrt{64}

                                       r = 8 centimeters

Result:

           The radius of the cylindrical vase is 8 centimeters, if the cylindrical vase holds 8,038.4 cubic centimeters of water and the height of the vase is 40 centimeters.

7 0
3 years ago
Please help!!!
Pie

Average speed = \frac{Total Distance}{Total Time}

Ishan's Speed uphill = 10mph

Time taken = 18 minutes = 18/60 = 3/10 hours

Now distance = rate × time

Distance traveled by Ishaan up hill = 10 × 3/10 = 3 miles

Now returning back home

Distance = 3 miles

Rate = 30 mph

So time taken = distance/ rate = 3/30= 1/10 hours = 1/10 ×60 = 6 minutes.

Now total distance traveled = 3 + 3 = 6 miles

Total time taken = 18 + 6 = 24 minutes = 24/60 = 2/5 hours

Average speed

= \frac{6}{0.4}

= 15 mph

Ishaan's average speed for the entire trip from home to the gift store and back is 15mph

5 0
3 years ago
The table shows the height of water in a pool as it is being filled. A table showing Height of Water in a Pool with two columns
arlik [135]

Answer:

A) The height of the water increases 2 inches per minute.

Step-by-step explanation:

Slope is the rate of change of height

m = (16 - 12)/(4 - 2) = 4/2 = 2

2 inch per min

Positive slope implies increase

6 0
3 years ago
Read 2 more answers
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