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2 years ago

Help I’m tired it’s 2:56am it’s due tomorrow morning !

Mathematics

1 answer:

guajiro [1.7K]2 years ago

8 0

Answer:

go to sleep just take the 0 and thinks for the points

Step-by-step explanation:

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the marks in an examination for a Physics paper have normal distribution with mean μ and variance σ2 . 10% of the students obtai

Blababa [14]

Let $X$ be the random variable for the number of marks a given student receives on the exam.

10% of students obtain more than 75 marks, so

$P(X>75)=P\left(\dfrac{X-\mu}\sigma>\dfrac{75-\mu}\sigma\right)=P(Z>z_1)=0.10$

where $Z$ follows a standard normal distribution. The critical value for an upper-tail probability of 10% is

$P(Z>z_1)=1-F_Z(z_1)=0.10\implies z_1=F_Z^{-1}(0.90)$

where $F_Z(z)=P(Z\le z)$ denotes the CDF of $Z$ , and $F_Z^{-1}$ denotes the inverse CDF. We have

$z_1=F_Z^{-1}(0.90)\approx1.2816$

Similarly, because 20% of students obtain less than 40 marks, we have

$P(X$

so that

$P(Z$

Then $\mu,\sigma$ are such that

$\dfrac{75-\mu}\sigma\approx1.2816\implies75\approx\mu+1.2816\sigma$

$\dfrac{40-\mu}\sigma\approx-0.8416\implies40\approx\mu-0.8416\sigma$

and we find

$\mu\approx53.8739,\sigma\approx16.4848$

3 0

3 years ago

Two angles are supplementary. The measure

BlackZzzverrR [31]

Answer:

57°

Step-by-step explanation:

Let's assume the measurement of the second angle is x.

so, following the problem

(2x + 9) + x = 180

2x + x = 3x

=> 3x + 9 = 180

=> 3x = 180 - 9

3x = 171

x = 171/3

x = 57°

57° is the smallest angle

5 0

2 years ago

50 POINTS!

nignag [31]

Answer:

im gussing sorry if its wrong :(

Step-by-step explanation:

1=a

2=d

3=b

4=c

4 0

2 years ago

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For the function f(x) = -2x?, if the domain is {-3, 0, 3}, find the range.<br> =-

Nutka1998 [239]

Answer:

here the Range ={6,0,-6}

4 0

2 years ago

Y + 2/5x =1 what does y equal?

bezimeni [28]

The answer is Y=-2/5x+1 :)

5 0

3 years ago

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