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denpristay [2]
3 years ago
15

I've only learned how to solve for a single variable. :')

Mathematics
1 answer:
MariettaO [177]3 years ago
7 0

Answer:brainliest plsssss

Step-by-step explanation:

1/2x+15=x

X+30=2x

30=2x-x

30=x

Number of girls in class

30-12=18

☆ the number of girls in his class are 18

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A new gas- and electric-powered hybrid car has recently hit the market. The distance traveled on 1 gallon of fuel is normally di
Doss [256]

Answer:

a) P [ Z > 70 ]  = 0.1075  or 10.75 %

b)  P [ Z < 60 ] = 0.1038   or  10.38 %

c)  P [ 55 ≤ Z ≤ 70 ] =  0.8882   or 88.82 %

Step-by-step explanation:

Normal Distribution  μ = 65    and σ = 4

a) The probability of the car travels more than 70 miles per gallon is:

P [ Z > 70 ]  =  (Z-μ) ÷ σ  ⇒   P [ Z > 70 ] = (70-65) ÷4     P [ Z > 70 ] = 1.25

the point 1.25 corresponds at values, from left tail up to 70 so we must go and look for the area for the point 1.24 which is 0.8925. Then we have the area or probability of all cars traveling up  to 70 miles therefore  we have to subtract 1 -0,8925

P [ Z > 70 ]  = 0.1075  or 10.75 %

b)The probability of the car travels less than 60 miles per gallon is:

P [ Z < 60 ]  = ( 60 - μ ) ÷  σ ⇒  P [ Z < 60 ] = (60-65)÷ 4    P [ Z < 60 ] = -1.25

Again -1.25 corresponds to 60 miles per gallon threfore we move to the left and find for point -1.26  which area is 0.1038 so

P [ Z < 60 ] = 0.1038     10.38 %

c) P [ 55 ≤ Z ≤ 70]

For  point  Z = 70 or 1.25 (case a above)  P [ Z ≤ 70] = (70-65)÷4  

P [ Z ≤ 70] = 1.25

In this case we got the whole area from the left tail up to 1.25

P [ Z ≤ 70]  = 0.8944 (includes the area of the point from the left tail up to the point assocciated to 55 miles and for that reason we have to subtract that area)

P [ Z ≥ 55 ]  = (55-65) ÷ 4     P [ Z ≥ 55 ] = -2.5  and the area is 0.0062

So P [ 55 ≤ Z ≤ 70 ] =  0.8944 - 0.0062  = 0.8882

8 0
3 years ago
What method would you choose to solve the equation 2x2 – 7 = 9? Explain why you chose this method.
Kisachek [45]
<span>This is a quadratic equation . We order to equate to zero

</span>2x²<span> – 7 = 9  
 </span>
2x² - 7-9 = 0
2x² - 16 = 0

This equation is a binomial
2* (x² - 8) = 0
<span>We choose the simplest method . The equation with practice it can be calculated in the memory
</span><span>
The product is equal to 0 if one of the factors is zero
</span>
2≠0  ∨     x² - 8 = 0
               x² = √8
               x = √8     ∨  x= - √8

Answer : x = √8 ∨ x = -√8
5 0
3 years ago
Read 2 more answers
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babymother [125]
120 would be the correct answer on apex
4 0
3 years ago
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A six-sided die is rolled. What is the probability that the number rolled will be an even number or a 6?
asambeis [7]

Answer:

1/2

Step-by-step explanation:

A six sided die has 1, 2, 3, 4, 5, 6. Out of those numbers, 3 of those are even numbers. Meaning you have a 3/6 chance. This 3/6 can be reduced to 1/2.

8 0
3 years ago
1 red bean for every 3 blue beans. Decimal equivalent of percent of red beans?
11111nata11111 [884]
The decimal equivalent is 0.25.
3 0
3 years ago
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