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Tresset [83]
3 years ago
8

Maria is training to be a long distance runner. She runs once every day. On the average, each day that Maria has run, she has im

proved her time by 20 seconds. Today she ran for the fifth time. Her time was 10 minutes 48 seconds. What was Maria's running time the first day she ran?
Mathematics
1 answer:
Sav [38]3 years ago
7 0

Answer:

9 mins and 8 secs

Step-by-step explanation:

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Find the probability that an SRS of 36 babies will have an average birthweight of over 3.9 kg. Write your answer as a decimal. R
Jlenok [28]

Complete question :

The birthweight of newborn babies is Normally distributed with a mean of 3.96 kg and a standard deviation of 0.53 kg. Find the probability that an SRS of 36 babies will have an average birthweight of over 3.9 kg. Write your answer as a decimal. Round your answer to two places after the decimal

Answer:

0.75151

Step-by-step explanation:

Given that :

Mean weight (m) = 3.96kg

Standard deviation (σ) = 0.53kg

Sample size (n) = 36

Probability of average weight over 3.9

P(x > 3.9)

Using the z relation :

Zscore = (x - m) / (σ / √n)

Zscore = (3.9 - 3.96) / (0.53 / √36)

Zscore = - 0.06 / 0.0883333

Zscore = −0.679245

Using the Z probability calculator :

P(Z > - 0.679245) = 0.75151

= 0.75151

3 0
3 years ago
Derive the equation of the parabola with a focus at (2, −1) and a directrix of y = −one half.
yKpoI14uk [10]
Basically, the parabola has to have all points that are equidistant from the focus and the directrix, the directrix being a horizontal line, and the focus being a point given. To derive an equation from this you need to use the distance formula which I'm guessing you already know because you're already in precalc.
The gist of it is that we have a random point on the parabola (x,y), and the point (x,y) will be equidistant from both the focus and the directrix. If we use the distance formula, you get something like this:
\sqrt{(y-(- \frac{1}{2} ))^2} = \sqrt{(x-2)^2+(y-(-1)^2}
The square root of y-(-1/2) coming from the directrix, and the righthand side of the equal sign being derived from the focus.
All you need to do is simplify now!
<span>(y+\frac{1}{2})^2 = (x-2)^2+(y+1)^2 \\\ y^2+y+ \frac{1}{4} = x^2-4x+4 + y^2+2y+1 \\\ -y-\frac{3}{4} = x^2-4x+4 \\\ -y-\frac{3}{4} = (x-2)^2 \\\ -y = (x-2)^2+\frac{3}{4} \\\ y = -(x-2)^2-\frac{3}{4}
</span>
Hope I helped! 
3 0
3 years ago
Read 2 more answers
Which value for x makes the sentence true?
Kipish [7]
I hope this helps you out

8 0
3 years ago
Read 2 more answers
HELP ASAP PLEASE!!!
Dvinal [7]

Answer:

B- False

Step-by-step explanation:


7 0
3 years ago
Read 2 more answers
In Olongapo City, a bump car ride costs
dimulka [17.4K]
Solve for n in 270=120 + n*10. 120 gives you first 30 minutes and n is the number of additional 10 minutes you ride. In this case you ride for 30+n*10 minutes. n = (270-120)/10 = 15. So the total time is 30+15*10 = 180 minutes. Or three hours!! That’s a lot of bumper cars!!
7 0
3 years ago
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