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3 years ago

I need help with these 2 questions, please also try to explain how to get it.

Mathematics

1 answer:

faust18 [17]3 years ago

6 0

The red lines signify congruency. Meaning, if one angle (say <EFD) is 75 and has one red line and <JAB also has one red line, it means it also equals 75.
Just like <GHF is 130 and has two lines, <JBC also has two red lines, so it also equals 130.

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The time for this event for boys in secondary school is known to possess a normal distribution with a mean of 460 seconds and a

AlekseyPX

Answer:

The time that the boys need to beat in order to earn a certificate of recognition from the fitness association is 511.264 seconds.

Step-by-step explanation:

We are given that the time for this event for boys in secondary school is known to possess a normal distribution with a mean of 460 seconds and a standard deviation of 40 seconds.

The fitness association wants to recognize the fastest 10% of the boys with certificates of recognition.

Let X = time for this event for boys in secondary school

SO, X ~ Normal( $\mu=460,\sigma^{2} =40^{2}$ )

The z-score probability distribution for normal distribution is given by;

Z = $\frac{X-\mu}{\sigma}$ ~ N(0,1)

where, $\mu$ = mean time = 460 seconds

$\sigma$ = standard deviation = 40 seconds

The Z-score measures how many standard deviations the measure is away from the mean. After finding the Z-score, we look at the z-score table and find the p-value (area) associated with this z-score. This p-value is the probability that the value of the measure is smaller than X, that is, the percentile of X.

Now, it is given that the fitness association wants to recognize the fastest 10% of the boys with certificates of recognition, which means;

P(X > x) = 0.10 {where x is the required time which boy need to beat}

P( $\frac{X-\mu}{\sigma}$ > $\frac{x-460}{40}$ ) = 0.10

P(Z > $\frac{x-460}{40}$ ) = 0.10

So, the critical value of x in the z table which represents the top 10% of the area is given as 1.2816, that is;

$\frac{x-460}{40} =1.2816$

${x-460}{} =1.2816\times 40$

$x$ = 460 + 51.264 = 511.264 seconds

Hence, the time that the boys need to beat in order to earn a certificate of recognition from the fitness association is 511.264 seconds.

8 0

3 years ago

Sally finds a coin with a radius of 1.5 centimeters and a thickness of 0.25 cm. It has a measured mass of 18.54 grams. How can S

mote1985 [20]

Answer:

Silver

Step-by-step explanation:

Find the volume of the coin

Volume of a cylinder

$\textsf{V}=\sf \pi r^2 h \quad\textsf{(where r is the radius and h is the height)}$

Given:

r = 1.5 cm
h = 0.25 cm

Substituting given values into the formula to find the volume:

$\sf \implies V=\pi (1.5)^2(0.25)$

$\sf \implies V=0.5625 \pi \:cm^3$

Find the density of the coin given it has a measured mass of 18.54 g

Density formula

$\sf \rho=\dfrac{m}{V}$

where:

$\rho$ = density
m = mass
V = volume

Given:

m = 18.54 g
$\sf V=0.5625 \pi \:cm^3$

Substituting given values into the density formula:

$\implies \sf \rho=\dfrac{18.54}{0.5625 \pi}$

$\implies \sf \rho=10.49149385\:g\:cm^{-3}$

Given:

$\textsf{Density of Lead}=\sf 11.3\:g\:cm^{-3}$

$\textsf{Density of Silver}=\sf 10.49\:g\:cm^{-3}$

Therefore, as $\sf \rho=10.49\:g\:cm^{-3}$ the coin is made from silver.

4 0

2 years ago

1) A basket of apples are given to a group of students. If 3 apples are given to each student, there will be 8 apples left. If 5

sattari [20]

Answer:

1) either 5 or 6 students in the group

2) 6 rooms are booked

Step-by-step explanation:

1) x students

3x + 8 = apples

5 (x-1) + y (the one get less than 5 apples)

3x + 8 = 5 (x - 1) + y

3x + 8 = 5x - 5 + y

2x + y = 13

X 1 2 3 4 5 6

Y 11 9 7 5 3 1

because y < 5 so x = 5 or x = 6

2) x rooms are booked

4x + 20 total students

8 (x-1) + y (the students in room not full))

4x + 20 = 8 (x-1) + y

4x + 20 = 8x - 8 + y

4x + y = 28

X 1 2 3 4 5 6

Y 24 20 16 12 8 4

y < 8 answer is 6 rooms

4 0

3 years ago

PLEASE HELP!!! IS Anyone good with probability ???!!!!!

Arada [10]

A) 1/3 B) 2/3 C) what is it asking D) 1/3 E1/3

6 0

3 years ago

Read 2 more answers

What percentage is 0.00042 ?

pogonyaev

Answer:

0.042%

How much is the decimal number 0.00042 written as (converted to) a percent value? Answer: 0.042%

Step-by-step explanation:

hope it helps please give me a heart

8 0

3 years ago

Read 2 more answers