15. At a football match, 10 men bought either a pie or a cup of
1 answer:
Answer:
8 pies and 2 coffees must have been bought.
Step-by-step explanation:
Given that:
10 men bought either a pie or a cup of coffee.
Cost per pie = 60p
Cost per coffee = 50p
Total amount spent = £5.80 * 100 = 580p
Let,
x be the number of pies
y be the number of coffees
According to given statement;
x+y = 10 Eqn 1
60x+50y=580 Eqn 2
Multiplying Eqn 1 by 50
50(x+y=10)
50x+50y=500 Eqn 3
Subtracting Eqn 2 from Eqn 3
(60x+50y)-(50x+50y) = 580-500
60x+50y-50x-50y=80
10x=80
Dividing both sides by 10
Putting x=8 in Eqn 1
8+y=10
y=10-8
y=2
Hence,
8 pies and 2 coffees must have been bought.
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The function
... f(x) = (x+2)/(x-1) = 1 + 3/(x-1)
is symmetrical about the line y=x, hence is its own inverse.
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... f'(x) -3/(x-1)²
so f'(2) is
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Answer:
The 96% confidence interval estimate for the mean daily number of minutes that BYU students spend on their phones in fall 2019 is between 306.65 minutes and 317.35 minutes.
Step-by-step explanation:
Confidence interval normal
We have that to find our level, that is the subtraction of 1 by the confidence interval divided by 2. So:
Now, we have to find z in the Ztable as such z has a pvalue of .
That is z with a pvalue of , so Z = 2.054.
Now, find the margin of error M as such
In which is the standard deviation of the population and n is the size of the sample.
The lower end of the interval is the sample mean subtracted by M. So it is 312 - 5.35 = 306.65 minutes
The upper end of the interval is the sample mean added to M. So it is 312 + 5.35 = 317.35 minutes
The 96% confidence interval estimate for the mean daily number of minutes that BYU students spend on their phones in fall 2019 is between 306.65 minutes and 317.35 minutes.