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Kazeer [188]
3 years ago
13

In a certain supermarket, a sample of 60 customers who used a self-service checkout lane averaged 5.2 minutes of checkout time,

with a standard deviation of 3.1 minutes. A sample of 72 customers who used a cashier averaged 6.1 minutes with a standard deviation of 2.8 minutes.
(a) Can you conclude that the mean checkout time is less for people who use the self-service lane?
(b) Can you conclude that if everyone used the self-service lane, that the mean checkout time would decrease? Consider the number of items checked out when formulating your answer.
Mathematics
1 answer:
bulgar [2K]3 years ago
7 0

Answer:

Step-by-step explanation:

I sample :

Sample size n1 = 60

Sample average = x bar = 5.2 minutes

STd deviation sample = s1 = 3.1 minutes

II sample:

n2 = 72

y bar = 6.1

s2 = 2.8 minutes

Mean difference = -0.9

Std error for difference = \sqrt{\frac{s_1^2}{n_1}+\frac{s_2^2}{n_2} } \\=0.5187

t statistic = mean diff/se = -1.735

p value = 0.0848

Since p >0.05 we accept null hypothesis that there is no difference between the two averages

Conclusion:

a) We cannot conclude that the mean checkout time is less for people who use the self-service lane

b) NO, we cannot conclude that if everyone used the self-service lane, that the mean checkout time would decrease

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erica [24]

Answer: the speed of the current is 9 mph.

Step-by-step explanation:

Let x represent the speed of the current.

A boat can travel 21 mph in still water. If it travels 270 miles with the current. It means that the total speed with which the boat travelled with the current is (21 + x) mph.

Time = distance/speed

Time spent by the boat in travelling 270 miles is

270/(21 + x)

In the same length of time, it travels 108 miles against the current. It means that the total speed with which the boat travelled against the current is (21 - x) mph.

Time = distance/speed

Time spent by the boat in travelling 108 miles is

108/(21 - x)

Since the time is the same, then

270/(21 + x) = 108/(21 - x)

270(21 - x) = 108(21 + x)

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108x + 270x = 5670 - 2268

378x = 3402

x = 3402/378

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7 0
3 years ago
Cal is measuring temperature changes in four substances over different time periods as part of a school project. Which data show
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Answer:

C) The third table. K= 5

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Step-by-step explanation:

1) Below there are the missing data:

A proportional relationship through a constant k. It is obtained when we divide:

k=\frac{y}{x}

2)In this case, when we divide the temperature (T) by the time (h).

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3)So, examining the table below we are searching for a ratio k common to all measures (temperatures over hour).

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Step-by-step explanation:

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