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ipn [44]
2 years ago
12

My teacher makes us read the book to learn and the book doesnt show how to solve something like this

Mathematics
1 answer:
Gre4nikov [31]2 years ago
7 0

If the mean score is 55% and the s.d. is 15%, then a test score of at least

55% + 1.5 × 15% = 77.5%

falls in the A range.

The next cutoff score is 0.5 s.d. from the mean, which is

55% + 0.5 × 15% = 62.5%

so any test score between 62.5% and 77.5% is in the B range.

The next cutoff is

55% - 0.5 × 15% = 47.5%

so a score between 47.5% and 62.5% gets a C.

The lower limit of the next range is

55% - 1.5 × 15% = 32.5%

so 32.5% - 47.5% gets a D.

Anything lower than 32.5% is an F.

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Can someone help me with number 4,5 and 6?
True [87]
4) You know slope-intercept form is y=mx+b. So using these two given points, you can find the slope! 

(-8,5)  (-3,10) [Use the y1-y2 over x1-x2 formula to solve for slope]

10 - 5         5
---------   = ----- = 1 
-3-(-8)         5

Hurray! You got a slope of one. Now substitute this back into your original equation:
y=mx+b --> y=1x+b 

Next, we find what our "b" is, or what our y-intercept is:
Using one of the previous points given, substitute them into the new equation:
[I used the point (-3, 10) ]

y=1x+b
10=1(-3)+b  SUBSTITUTE 
10=-3+b     MULTIPLY
10=-3+b
+3   +3    ADD
----------
13=b     SIMPLIFY 

So, now we have our y-intercept. Use this and plug it into the equation:
y=1x+b --> y=1x+13 

y=1x+13 is our final answer.



5) So for perpendicular lines, your slope will be the opposite reciprocal of the original slope. (Ex: Slope is 2, but perpendicular slope is -1/2) 

We have the equation y= 3x-1, so find the reciprocal slope! 
--> y=-1/3x-1 

Good! Now we take our given point, (9, -4) and plug it into the new equation:

y=-1/3x-1
-4=-1/3(9)+b   SUBSTITUTE and revert "-1" to "b", for we are trying to find the y-     -4=-3+b          intercept of our perpendicular equation. 
+3   +3            ADD
--------
-1=b    SIMPLIFY 

So, our final answer is y=-1/3x+(-1)

6) I don't know, sorry! :( 
4 0
3 years ago
The temperature T in degrees Celsius of a liquid t minutes after heating is given by the formula T=8√t. When is the temperature
Advocard [28]
T=8√t
T=temperature
t=time in minutes.
If T=48, we have to calculate the time.

48=8√t
(48)²=(8√t)²
2304=64t
t=2304 / 64=36

answer: 48 degrees Celsius will be reached in 36 minutes. 
3 0
2 years ago
Find the maximum or minimum of the following quadratic function: y = 16x2+ 40x + 25.
Irina-Kira [14]

the answer to your question is c. -25


4 0
3 years ago
Which of the following is the correct factorization of the polynomial below? 8x3 + 64y3 A. (4x + 4y) (2x+8y) B. (2x + 4y)(4x2 -
stepladder [879]

Answer:

B. (2x+4y)(4x2-8xy+16y2)

Step-by-step explanation:

hope this helps!

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3 years ago
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