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telo118 [61]
2 years ago
14

Many states assess the skills of their students in various grades. One of the tests provided by a national association assesses

the reading skills of 12th-grade students. In a recent year, the national mean score was 286 and the standard deviation was 38. Assuming that these scores are approximately Normally distributed, N(286, 38), use the 68-95-99.7 rule to give a range of scores that includes 95% of these students.
Mathematics
1 answer:
Alik [6]2 years ago
3 0

Answer:

95% of these scores are between 210 and 362.

Step-by-step explanation:

The Empirical Rule 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 = 286, Standard deviation = 38

Use the 68-95-99.7 rule to give a range of scores that includes 95% of these students.

This is within 2 standard deviations of the mean. So

286 - 2*38 = 286 - 76 = 210

286 + 2*38 = 286 + 76 = 362

95% of these scores are between 210 and 362.

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A culture started with 5000 bacteria. after 4 hours, it grew to 6000. Predict how many bacteria will be present after 17 hours
kykrilka [37]

Answer:

A culture started with 5000 bacteria. after 4 hours, it grew to 6000.

=> Increasing rate = difference/time = (6000 - 5000)/4 = 250 bacteria/hour

=> The number of bacteria after 17 hours:

N = 5000 + 250 x 17 = 9250 bacteria

Hope this helps!

:)

4 0
3 years ago
Read 2 more answers
On a recent trip to the convenience​ store, you picked up 3 gallons of​ milk, 6 bottles of​ water, and 8 ​snack-size bags of chi
SVETLANKA909090 [29]

Answer:

The answers to the question are as follows

A bottle of water costs  $2.00

A gallon of mik cots $4.10 and

A bag of chips costs $1.00

Step-by-step explanation:

To solve the question, it is important to note that it is a word problem hence we read the question carefully to clearly understnd and be able to interprete the message from any perspective

We list out the variables as follows

Number of gallons of milk = 3

Number of bottles of water = 6

Number of chips bags = 8

Bill before tax = $32.30

Price of a bottle of water = twice the price of a bag of chips

Price of a gallon of mlk  = $ 2.10 + price of a bottle of water

Therefore in order to find out how much each item costs let us call the price of  bottle of water $x say

This means that the price of a bag of chips = x/2 and

The price of a gallon of milk = x + $2.10

Therefore  we have by multiplying the prices of the items to their respective quantities and summing up

$(6x + 3(x+2.1)+ 8 x/2) = $32.3

This gives by expanding the values 6x+3x+6.3+4x =32.3

13x+6.3 =32.3

13x = 32.3 - 6.3 = 26

Dividing both sides by 13 gives

x = $2.00

This means that a bottle of water costs  $2.00

A gallon of mik cots $2.00+$2.10 = $4.10

A bag of chips costs x/2 which is equal to $2.00/2 = $1.00

8 0
3 years ago
In 1990, the cost of tuition at a large Midwestern university was $99 per credit hour. In 2003, tuition had risen to $268 per cr
vodka [1.7K]

Answer:

63%

Step-by-step explanation:

<em>From the question, we aim to find the percent increase in the tuition</em>

Given data

initial cost= $99 per credit hour

Final cost=  $268 per credit hour

% increase= (Final - initial )/initial *100

substitute

% increase= (268- 99 )/268 *100

% increase= 169 /268 *100

% increase= 0.630*100

% increase= 63%

Hence the increase in the tuition from 1990 to 2003 is 63%

5 0
2 years ago
Simplify 9a+3+2a+10<br><br><br><br> thx
a_sh-v [17]
Hey there 

9a+3+2a+10
You have to collect like terms 

To simplify you have to add 9a and 2a. Then 3 and 10 
9a+2a= 11a 
10+3= 13 

The answer is 11a+13

hope this helps  <span />
7 0
3 years ago
Read 2 more answers
Melanie eats 1.5 pounds of cereal each week. Which model below best represents the number of pounds of cereal she eats in .5 wee
Katena32 [7]
For this case, the first thing we must do is define a variable.
 We have then:
 x: number of weeks
 y: amount of cereal that Melanie eats
 We now write the function that models the problem:
 y = 1.5x&#10;
 Then, for 5 weeks we have:
 y = 1.5 (5)&#10;&#10;y = 7.5 pounds
 Answer:
 
A model that best represents the number of pounds of cereal she eats is:
 
y = 1.5x&#10;
 For 5 weeks we have:
 
y = 7.5 pounds
5 0
3 years ago
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