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Flura [38]
3 years ago
9

In a study of 250 adults, the mean heart rate was 70 beats per minute. Assume the population of heart rates is known to be appro

ximately normal with a standard deviation of 12 beats per minute. What is the 99% confidence interval for the mean beats per minute?
68.9 − 76.3
70 − 72
61.2 − 72.8
68 − 72
Mathematics
2 answers:
pantera1 [17]3 years ago
4 0
The z score for a confidence level of 99% is 2.575.. You need to know this to complete this type of problem.. the other two commonly used confidence levels are 90% and 95% having z scores of 1.645 and 1.96 respectively. You need to memorize this!

To find the confidence interval, it will be defined as the sample mean plus/minus the margin of error.. Now to find the margin of error, divide the standard deviation of 12 by the square root of the number of elements in your sample(√250). Then take that result and multiply it by the Z score I mentioned above for a 99% confidence level.


In this case: the sample mean is 70 and the margin of error is approximately 1.95

So to calculate the confidence interval, do the following:
70 - 1.95 = 68.05 rounded to the nearest whole number is 68
70 + 1.95 = 71.95 rounded to the nearest whole number is 72

Looks like that would be the last choice. hope this helps.. it's been awhile since my work with statistics :-)
strojnjashka [21]3 years ago
3 0

Answer:

68-72 will be your answer

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Emilio’s paycheck was $305.25, and he makes $9.25 per hour. How many hours did Emilio work?
Anastaziya [24]
$305.25 divided by $9.25 equals 33, so he worked 33 hours... hope this helped.
5 0
3 years ago
Read 2 more answers
PLZZZZ HELPPPPPPPPP!!!! a survey asks teachers and students whether they would like the new school mascot to be a Viking or a Pa
VARVARA [1.3K]

Answer:

B

Step-by-step explanation:

Two events A and B are called independent, when

P(B|A)=P(B),

where P(B|A) is the probability that B occurs given that A has already occurred.

A = randomly selected person is a student

B = randomly selected person prefer "Vikings"

B|A = randomly selected student prefer "Vikings"

Probabilities:

P(A)=\dfrac{100}{125}=\dfrac{4}{5}=0.8\\ \\P(B|A)=\dfrac{80}{85}=\dfrac{16}{17}\approx 0.94

Since

0.80\neq 0.94

we can state that events are not independent.

8 0
3 years ago
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( -3/4 + 4/3) + i =0 Show your work. (Please help)
Effectus [21]

Answer:

i = -7/12

Step-by-step explanation:

(-3/4 + 4/3) + i = 0

(-9/12 + 16/12) + i = 0

7/12 + i = 0

i = -7/12

6 0
2 years ago
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Write 1,334,457. in 12 expanded form
Alchen [17]
1,000,000+3000,000+30,000+4,000+400+50+7
8 0
3 years ago
Sid starts with savings of £13
vfiekz [6]

Answer:

after 6 weeks

Step-by-step explanation:

Sid and Tim starts saving each week.

Sid starts his savings with initial amount of £13.00

Tim starts his saving with initial amount of £00.00

Each week from now Sid will save = £3.50

Tim will save each week = £3.00

Let's assume after 'x' weeks the amount of Sid would be = £ (13 + 3.50x)

and the amount of Tim's saving after x weeks = £ (3x)

The ratio of their savings in x weeks would be = 17 : 9

Now the expression we get,

(13 + 3.50x) : (3x) = 17 : 9

\frac{13+3.50x}{3x}=\frac{17}{9}

9(13 + 3.50x) = 17(3x)

117 + 31.5x = 51x

117 = 51x - 31.5x

117 = 19.5x

x=\frac{117}{19.5}

x = 6

After 6 weeks the savings of Tim and Sid would be in the ratio of 17 : 9.

5 0
2 years ago
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