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vitfil [10]
2 years ago
15

David made an error when determining the product of (–2.5)(–8.3). Step 1: (–2.5)(–8.3) = (–8.3)(–2.5) Step 2: = (–8.3)(–2) + (–8

.3)(–0.5) Step 3: = (–16.6) + (–4.15) Step 4: = –20.75 In which step did David make his first error?​
Mathematics
1 answer:
kiruha [24]2 years ago
8 0

Answer:

David make his first error at Step 3

Step-by-step explanation:

We need to determine the error David made when finding the product of (-2.5)(-8.3)

He did the following steps

Step 1: (–2.5)(–8.3) = (–8.3)(–2.5)

Step 2: = (–8.3)(–2) + (–8.3)(–0.5)

Step 3: = (–16.6) + (–4.15)

Step 4: = –20.75

David made a mistake in Step 3

When we multiply (-1) with (-1) we get + instead of - sign. The correct step 3 would be:

Step 3: =(16.6)(4.15)

Step 4: =20.75

So, David make his first error at Step 3

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Points a, b, and c are midpoints of the sides of right triangle def. Which statements are true select three options. A B C D E
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Answer : The correct statements are,

AC = 5 cm

BA = 4 cm

The perimeter of triangle ABC is 12 cm.

Step-by-step explanation :

As we know that a, b, and c are midpoints of the sides of right triangle that means midpoint divide the side in equal parts.

Now we have to calculate the sides of triangle ABC by using Pythagoras theorem.

Using Pythagoras theorem in ΔACF :

(AC)^2=(FA)^2+(CF)^2

Now put all the values in the above expression, we get the value of side AC.

(AC)^2=(3)^2+(4)^2

AC=\sqrt{(9)^2+(16)^2}

AC=5cm

Using Pythagoras theorem in ΔDAB :

(Hypotenuse)^2=(Perpendicular)^2+(Base)^2

(BD)^2=(AD)^2+(BA)^2

Now put all the values in the above expression, we get the value of side BA.

(5)^2=(3)^2+(BA)^2

BA=\sqrt{(5)^2-(3)^2}

BA=4cm

Using Pythagoras theorem in ΔBEC :

(Hypotenuse)^2=(Perpendicular)^2+(Base)^2

(BE)^2=(CE)^2+(CB)^2

Now put all the values in the above expression, we get the value of side CB.

(5)^2=(4)^2+(CB)^2

CB=\sqrt{(5)^2-(4)^2}

CB=3cm

Now we have to calculate the perimeter of ΔABC.

Perimeter of ΔABC = Side AB + Side CB+ Side AC

Perimeter of ΔABC = 4 + 3 + 5

Perimeter of ΔABC = 12 cm

Now we have to calculate the area of ΔABC.

Area of ΔABC = \frac{1}{2}\times 4\times 3=6cm^2

Now we have to calculate the area of ΔDEF.

Area of ΔDEF = \frac{1}{2}\times 8\times 6=24cm^2

Area of ΔABC = \frac{6}{24}\times Area of ΔDEF

Area of ΔABC = \frac{1}{4} Area of ΔDEF

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2 years ago
What is the product? (5r − 4)(r2 − 6r + 4)
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(5r - 4)(r² - 6r + 4)

distributive property of multiplication.

5r(r² - 6r + 4) - 4(r² - 6r + 4)
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group like terms and simplify.

5r³ - 30r² - 4r² + 20r + 24r - 16

5r³ - 34r² + 44r - 16  Choice A.
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2 years ago
Read 2 more answers
The manager of a paint supply store wants to estimate the actual amount of paint contained in 1​-gallon cans purchased from a na
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Answer:

a. 95​% confidence interval estimate for the population mean amount of paint included in a​ 1-gallon can is 0.998±0.0055

b.  <u>No,</u> because a​ 1-gallon paint can containing exactly​ 1-gallon of paint lies <u>within</u> the 95​% confidence interval.

c. Yes.  The population amount of paint per can is assumed normally distributed, because confidence interval calculations assume normal distribution of the parameter.

d. 90% confidence interval is 0.998±0.0046. ​The answer in b. didn't change; 1-gallon paint can containing exactly​ 1-gallon of paint lies <u>within</u> the 90​% confidence interval. The manager <u>doesn't have</u> a right to complain to the manufacturer.

Step-by-step explanation:

Confidence Interval can be calculated using M±ME where

M is the sample mean amount of paint per 1​-gallon can (0.998 gallon)

ME is the margin of error from the mean

And margin of error (ME) can be calculated using the equation

ME=\frac{z*s}{\sqrt{N} } where

  • z is the corresponding statistic in the 95% confidence level (1.96)
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Then ME=\frac{1.96*0.02}{\sqrt{50} }≈0.0055

95% confidence interval is 0.998±0.0055

90% confidence interval can be calculated similary, only z statistic is 1.64.

ME=\frac{1.64*0.02}{\sqrt{50} }  ≈0.0046

90% confidence interval is 0.998±0.0046

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Camille knew that a triangle had one side with a length of 16 inches and another side with a length of 20 inches. She did not kn
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Answer:

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Step-by-step explanation:

Dan has 2 1/2 cookies and ate 1/2, so we can just subtract the 2 1/2-1/2

which cancels out the 1/2, which is the fractional part.

He has 2 cookies left.

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2 years ago
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