What are the roots of a quadratic equation?

A sleep time of 15.9 hours per day for a newborn baby is at the 10h percentile of the distribution of sleep times for all newbor

Step2247 [10]

The mean time in hours per day for newborn babies is 16.5 hours ⇒ D

Step-by-step explanation:

A sleep time of 15.9 hours per day for a newborn baby is at the 10th

percentile of the distribution of sleep times for all newborn babies

Assuming the distribution is normal with a standard deviation of

0.5 hour

To find the mean time let us do that

1. Use the normal distribution table to find the corresponding z-score

for 10th percentile

2. Use the rule μ = x - zσ, where μ is the mean, σ is the standard

deviation and x is the score

3. Substitute the values of x, σ and z in the rule to find μ

Look to the normal distribution table to find z-score that equivalent

to the area = 10/100 = 0.1 (10th percentile)

∵ z-score = -1.28

∵ σ = 0.5 hour

∵ x = 15.9

∵ μ = x - zσ

- Substitute the values in the rule

∴ μ = 15.9 - (-1.28)(0.5)

∴ μ = 15.9 + 0.64

∴ μ = 16.54 ≅ 16.5 hours

The mean time in hours per day for newborn babies is 16.5 hours

Learn more:

You can learn more about the normal distribution curve in brainly.com/question/8799684

#LearnwithBrainly

6 0

3 years ago

A rectangular carpet measures 12 m by 5 m.

Zepler [3.9K]

Answer:

$\frac{1}{15}$

Step-by-step explanation:

Area of the Rectangular Carpet=12*5=60m²

Area of the Square rug=2*2=4m²

Expressing the area of the rug as a fraction of the total area of the carpet, we have:

$\frac{\text{Area of Rug}}{\text{Area of Carpet}}=\frac{4}{60}\\=\frac{1}{15}$ .

The fraction of the carpet that is covered by the rug is $\frac{1}{15}$ .

8 0

3 years ago

A bakery recorded the number of muffins and bagels it sold for a seven day period. For the data presented, what does the value o

atroni [7]

Answer:

Mean of bagel

Step-by-step explanation:

Working out each of the statically summaries Given in the option :

Mean of muffin :

Mean = Σx / n

n = sample size

(61 + 20 + 32 + 58 + 62 + 61 + 56) / 7

= 350 / 7

= 50

Mean of bagel :

Mean = Σx / n

n = sample size

(34 + 45 + 43 + 42 + 46 + 72 + 75) / 7

= 357 / 7

= 51

Hence, from the result obtained, we could see that the value of 51 summarizes the mean of bagel.

3 0

3 years ago

I'm confused. Can someone help?

VARVARA [1.3K]

a.

The polynomial w^2+18w+84 cannot be factored

The perfect square trinomial is w^2+18w + 81

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The reason the original can't be factored is that solving w^2+18w+84=0 leads to no real solutions. Use the quadratic formula to see this. The graph of y = x^2+18x+84 shows there are no x intercepts. A solution and an x intercept are basically the same. The x intercept visually represents the solution.

w^2+18w+81 factors to (w+9)^2 which is the same as (w+9)(w+9). We can note that w^2+18w+81 is in the form a^2+2ab+b^2 with a = w and b = 9

================================================

b.

The polynomial y^2-10y+23 cannot be factored

The perfect square trinomial is y^2-10y + 25

---------

Using the quadratic formula, y^2-10y+23 = 0 has no rational solutions. The two irrational solutions mean that we can't factor over the rationals. Put another way, there are no two whole numbers such that they multiply to 23 and add to -10 at the same time.

If we want to complete the square for y^2-10y, we take half of the -10 to get -5, then square this to get 25. Therefore, y^2-10y+25 is a perfect square and it factors to (y-5)^2 or (y-5)(y-5)

8 0

3 years ago

What is 45 as a fraction?

Rama09 [41]

A whole number is always written as itself over one.

45/1

Answer: 45/1

7 0

3 years ago