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solmaris [256]
3 years ago
11

Lin Ying belongs to an athletic club. In 800 m races her times are normally distributed with mean 128 seconds and standard devia

tion
4 seconds.
(a) What is the probability of her time in an 800 being between 120 and 130 seconds?
(b) What time will she beat in 70% of her races?
Julie belongs to the same club. In 800 m races 85% of her times are less than 140 seconds and 70% are less than 135 seconds. Her times are normally distributed.
(c) Find the mean and standard deviation of Julie's times, each correct to two significant figures.
(d) What is the probability that in an 800 m race Lin Ying will beat Julie?
(e) The club has to choose one of these two athletes to enter a major competition. In order to qualify for the final rounds it is necessary to achieve a time of 114 seconds or less in the heats. Which athlete should be chosen and why?
Mathematics
2 answers:
Setler [38]3 years ago
3 0

Answer:

Nine of the times for the first race were at least 16 seconds

Step-by-step explanation:

Here we have from the scatter plot, the times are given as

Time               Frequency

19                          2

18                          2

17                          2

16                          3

15                          1

Therefore, total number of times that are above 16 seconds in the first race is

3 + 2 + 2 + 2 = 9

Therefore, the first option is correct

insens350 [35]3 years ago
3 0

Answer:

Step-by-step explanation:

The answer is below. Plesetake a look and it will help you

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Simplify (x − 4)(3x2 − 6x + 2). 3x3 + 6x2 − 22x + 8 3x3 − 18x2 + 26x − 8 3x3 − 18x2 − 22x − 8 3x3 + 6x2 + 22x + 8
kogti [31]

Answer:

3x^3-18x^2+26x-8

Step-by-step explanation:

(x-4)(3x^2-6x+2)

3x^3-6x^2+2x-12x^2+24x-8

3x^3-18x^2+26x-8

5 0
2 years ago
What did the term 4x have in common (have the same) with x,120x, -3x?
Lera25 [3.4K]

Answer:

They're all like terms (x)

7 0
3 years ago
Read 2 more answers
The difference between the roots of the quadratic equation x2 -14x +q =0 is 6. Find q
Irina-Kira [14]

9514 1404 393

Answer:

  q = 40

Step-by-step explanation:

When the quadratic has roots p and r, it can be factored as ...

  (x -p)(x -r) = x² -(p+r)x +pr

So, the sum of the roots is 14, and their difference is 6. This lets us find the roots from ...

  p + r = 14

  p - r = 6

  2p = 20 . . . add the two equations

  p = 10

  r = 14 -p = 4

The value of interest is then ...

  q = pr = (10)(4)

  q = 40

__

The graph shows the roots to be 4 and 10, as we found.

3 0
3 years ago
I need a written response to solve all 4 steps
borishaifa [10]

Answer:

a. -2

b. s = 2 and y = -5

c. (2.5, -9)

d. -7x - 2

Step-by-step explanation:

a. In the image, I have used rise over run, which is -8/4 or -2.

b. slope formula is mx + b = y, where m is slope and b is the y-intercept. In the equation 2x - 5y = -10, 2 is the slope and -5 is the y-intercept.

c. Plug in all given numbers into an equation and the ones you do not have will be in the points you need it to be. Once you graph the equation you will receive (2.5, -9).

d. y = mx + b

   5 = (-7)(-1) + b

   5 = 7 + b

   -2 = b

y = -7x - 2  

6 0
2 years ago
(CO 4) In a sample of 8 high school students, they spent an average of 24.8 hours each week doing sports with a sample standard
AveGali [126]

Answer:  

(22.12, 27.48)

Step-by-step explanation:

Given : Significance level : \alpha: 1-0.95=0.05

Sample size : n= 8 , which is a small sample (n<30), so we use t-test.

Critical values using t-distribution: t_{n-1,\alpha/2}=t_{7,0.025}=2.365

Sample mean : \overline{x}=24.8\text{ hours}

Standard deviation : \sigma=3.2\text{ hours}

The confidence interval for population means is given by :-

\overline{x}\pm t_{n-1,\alpha/2}\dfrac{\sigma}{\sqrt{n}}

i.e. 24.8\pm(2.365)\dfrac{3.2}{\sqrt{8}}

24.8\pm2.67569206001\\\\\approx24.8\pm2.68\\\\=(24.8-2.68, 24.8+2.68)=(22.12, 27.48)

Hence, the 95% confidence interval, assuming the times are normally distributed.=  (22.12, 27.48)

6 0
2 years ago
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