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Angelina_Jolie [31]

3 years ago

5

On the first math test, Keiko answered 19 out of 20 correct. On which test did she get a better grade? Write a ratio in faction

form to compare the number correct to the total questions for each test.

2 answers:

frosja888 [35]3 years ago

3 0

The fraction for is 19/20

klasskru [66]3 years ago

3 0

It is nineteen out of twenty

You might be interested in

<img src="https://tex.z-dn.net/?f=%20-%2022%20%3D%2011%20-%206a" id="TexFormula1" title=" - 22 = 11 - 6a" alt=" - 22 = 11 - 6a"

jolli1 [7]

<h3><u>The value of a is equal to 5.5</u></h3>

-22 = 11 - 6a

<em><u>Add 6a to both sides.</u></em>

6a - 22 = 11

<em><u>Add 22 to both sides.</u></em>

6a = 33

<em><u>Divide both sides by 6.</u></em>

a = 5.5

7 0

3 years ago

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.

<u><em>Let X = time for this event for boys in secondary school</em></u>

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.

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

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

<em>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;</em>

<em> </em> $\frac{x-460}{40} =1.2816$

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

<em> </em> $x$ = 460 + 51.264 = <u>511.264 seconds</u>

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

You collect baseball cards and buy sealed packs from the grocery store and clearly have no idea which cards are inside (nor if t

ololo11 [35]

Answer:

(a) 0.9607

(c) 0.04

(d) 0.8184

(e) 0.074

(f) 0.0853/e^0.8;

750 cards

Step-by-step explanation:

Let the probability of success of a valuable card be p

p= 1/250 = 0.004,

q = 1-p = (249/250)

(a) There are 10 cards in one pack

The probability that there are no valuable card is given by:

Pr(X= 0) = 10C0 × (1/250)^0 ×(249/250)^10

10C0 = 10 combination 0= 10!/10!0!

=1

Pr (X= 0) = (249/250)^10

Pr (X=0) = 0.9607

(c) Expected number of valuable card is given by:

E(X) = np , n= 10, p= 1/250

E(X) = 10 × 1/250 = 1/25 = 0.04

(d) 5 packages means 5 × 10= 50 cards

Pr(X=0) = 50C0 × (1/250)^0 ×(249/250)^50

50C0 = 50!/50! ×0!=1

Pr (X=0) = (249/250)^50

Pr (X= 0) =(0.996)^50

Pr (X=0) = 0.8184

(e) For this case we use the Binomial Distribution

2 packages 2 × 10 = 20 cards

n = 20 , x = 1

We use:

P(X=1) = 20C1 × (1/250)^ 1 × (249/250)^19

Pr (X=1) = 20C1 × (1/250)^1 × (249/250)^19

Pr (X=1) = 20 × (1/250)¹ × (249/250)^19

Pr (X= 1 )= 0.074

(f) 20 packages = 200 cards

For this we apply Poisson distribution

P(X=3) = (e ^-h × h ^x) / x!

Where h = np = 200/250 = 0.8

P(X=3) = e^-0.8 × (0.8)^3 / 3!

P(X=3) = 0.991 × 0.512/6

P(X=3) = 0.0846

3 = n p

n = 3/p = 3 /0.04

n = 750 cards

8 0

4 years ago

What does the notation P(B|A) mean ?

Inessa [10]

Answer:

P(B|A) means "Event B given Event A" In other words, event A has already happened, now what is the chance of event B? P(B|A) is also called the "Conditional Probability" of B given A.

Step-by-step explanation:

please give me brainlist and follow.

3 0

3 years ago

Read 2 more answers

A circular pond has a diameter of 17 feet. There is pathway around the rim of the pond. What is the length of the pathway?

NeX [460]

Answer:

53.38ft

Step-by-step explanation:

By it asking the length of the pathway, in math terms its just asking you the circumfrence of the pond.

C = 2( $\pi$ )(r)

C = 2(3.14)(17/2)

C = 2(3.14)(8.5)

C = 53.38ft

6 0

3 years ago

Read 2 more answers