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nydimaria [60]
2 years ago
13

The time to complete an exam is approximately Normal with a mean of 70 minutes and a standard deviation of 10 minutes. Using the

68-95-99.7 rule, what percentage of students will complete the exam in less than 60 minutes
Mathematics
1 answer:
MatroZZZ [7]2 years ago
5 0

Answer:

16% of students will complete the exam in less than 60 minutes

Step-by-step explanation:

The Empirical Rule(68-95-99.7) states that, for a normally distributed random variable:

68% of the measures are within 1 standard deviation of the mean.

95% of the measures are within 2 standard deviation of the mean.

99.7% of the measures are within 3 standard deviations of the mean.

In this problem, we have that:

Mean = 70

Standard deviation = 10

What percentage of students will complete the exam in less than 60 minutes

60 = 70-10

So 60 is one standard deviation below the mean

By the Empirical Rule, 68% of the measures are within 1 standard deviation of the mean, that is, from 60 to 80 minutes. The other 100-68 = 32% is outside this interval. Since the normal distribution is symmetric, 16% of those are below 60 and 16% of those are above 80.

16% of students will complete the exam in less than 60 minutes

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How many days will it take for a sum of $4,000 to earn $80 interest if it is deposited in a bank paying ordinary simple interest
Maksim231197 [3]

Answer:

It will take 146 days to earn an interest of $80.

Step-by-step explanation:

The simple interest formula is:

I=\frac{P\times r\times t}{100}

It is provided that:

I = $80

P = $4,000

r = 5% p.a.

Compute the time required as follows:

I=\frac{P\times r\times t}{100}

t=\frac{I\times 100}{P\times r}

  =\frac{80\times 100}{4000\times 5}\\\\=0.4\ \years\\\\=0.4\times 365\ days\\\\=146\ days

Thus, it will take 146 days to earn an interest of $80.

4 0
2 years ago
Area of rectangular figures​
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Answer:

531 in^2

Step-by-step explanation:

21 x 18 = 378 in^2

17 x 9 = 153 in^2

378 + 153 = 531 in^2

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2 years ago
linda is building a rectangular playhouse. the width is x feet. the length is x + 3 the distance around the base of the playhous
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No. The value of x is 7.5 feet.
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3 years ago
Two boys and three girls are auditioning to play the piano for a school production. Two students will be chosen, one as the pian
finlep [7]

Answer:

30% is the correct answer.

Step-by-step explanation:

Total number of boys = 2

Total number of girls = 3

Total number of students = 5

To find:

Probability that the pianist will be a boy and the alternate will be a girl?

Solution:

Here we have to make 2 choices.

1st choice has to be boy (pianist) and 2nd choice has to be girl (alternate).

\bold{\text{Required probability }= P(\text{boy as pianist first}) \times P(\text{girl as alternate})}

Formula for probability of an event E is given as:

P(E) = \dfrac{\text{Number of favorable cases}}{\text {Total number of cases}}

For P(\text{boy as pianist}), number of favorable cases are 2 (total number of boys).

Total number of cases = Total number of students i.e. 5

So, P(\text{boy as pianist}) is:

P(\text{boy as pianist}) = \dfrac{2}{5}

For P(\text{girl as alternate}), number of favorable cases are 3 (total number of girls).

Now, one boy is already chosen as pianist so Total number of cases = Total number of students left i.e. (5 - 1) = 4

P(\text{girl as alternate}) = \dfrac{3}{4}

So, the required probability is:

\text{Required probability } = \dfrac{2}{5}\times \dfrac{3}{4} = \dfrac{3}{10} = \bold{30\%}

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3 years ago
Solve the following system by graphing and identify the point of intersection -5x+2y=-4 2x-y=2
FrozenT [24]

Answer: Point of intersection (0, -2)

Step-by-step explanation:

8 0
1 year ago
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