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Nitella [24]
3 years ago
8

e lifetimes of lightbulbs of a particular type are normally distributed with a mean of290 hours and astandard deviation of6 hour

s. What percentage of the bulbs have lifetimes that lie within 1 standarddeviation to either side of the mean
Mathematics
1 answer:
Tcecarenko [31]3 years ago
8 0

Answer:

Step-by-step explanation:

p(\overline{X}-\sigma \leq X \leq \overline{X}+\sigma)\\\\=p(\dfrac{\overline{X}-\sigma -\overline{X} }{\sigma} \leq  Z \leq \dfrac{\overline{X}+\sigma -\overline{X} }{\sigma} )\\\\=p ( -1 \leq Z \leq 1)\\\\=2*(\ p (Z \leq 1)-0.5)\\\\=2*(0.8413-0.5)\\\\=0.6826\\\\\approx{68\%}

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What is the length side of a triangle that has vertices at (-5, -1), (-5, 5), and (3, -1)?
Rasek [7]

The side lengths of triangle are 6 units, 8 units and 10 units.

<u>SOLUTION: </u>

Given that, we have to find what is the length side of a triangle that has vertices at (-5, -1), (-5, 5), and (3, -1)  

We know that, distance between two points P\left(x_{1}, y_{1}\right) \text { and } Q\left(x_{2}, y_{2}\right) is given by  

P Q=\sqrt{\left(x_{2}-x_{1}\right)^{2}+\left(y_{2}-y_{1}\right)^{2}}

Now,  

\begin{array}{l}{\text { Distance between }(-5,-1) \text { and }(-5,5)=\sqrt{(-5-(-5))^{2}+(5-(-1))^{2}}} \\\\ {\qquad \begin{array}{l}{=\sqrt{(-5-(-5))^{2}+(5-(-1))^{2}}} \\\\ {=\sqrt{(0)^{2}+(5+1)^{2}}=\sqrt{(6)^{2}}=6} \\\\ {=\sqrt{(-5)^{2}+(5+1)^{2}+(5-(-1))^{2}}} \\\\ {=\sqrt{(-8)^{2}+(5+1)^{2}}=\sqrt{64+36}=\sqrt{100}=10} \\\\ {=\sqrt{(3-1)^{2}+(-1-(-1))^{2}}} \\\\ {=\sqrt{(5+3)^{2}+(0)^{2}}=\sqrt{(8)^{2}}=8}\end{array}}\end{array}

8 0
3 years ago
1-Solve: m - 9 = -13
timofeeve [1]
1: m=-4
2: b=-4
3: -9=k
4: C=-11.4
5:X<10
4 0
3 years ago
A triangle that has no sides of equal length and one angle greater than 90° is which type of triangle?
Ganezh [65]

Answer:

It’s a obtuse triangle/scalene triangle

Step-by-step explanation:

Giving the information that is provided if the sides are not equal then it seems to be that the correct answer would be Obtuse Scalene

6 0
2 years ago
Read 2 more answers
Is the difderence of 1.48-0.25 less than or greater than one? Explain
luda_lava [24]
Greater than 1.Because 1.25-0.25=1.23.That's it.
6 0
3 years ago
Read 2 more answers
A virus that initially infected four people is spreading at a rate of 15% each week.
Solnce55 [7]

Answer:

"f(x) = 4(1.02)7x; spreads at a rate of approximately 2% daily"

Step-by-step explanation:

<u>Complete Question:</u>

A virus that initially infected four people is spreading at a rate of 15% each week. The following function represents the weekly spread of the virus: f(x) = 4(1.15)x. Rewrite the function to show how quickly the virus spreads each day and calculate this rate as a percentage.

f(x) = 4(1.15)7x; spreads at a rate of approximately 1.5% daily

f(x) = 4(1.02)7x; spreads at a rate of approximately 2% daily

f(x) = 4(1.157)x; spreads at a rate of approximately 2.66% daily

f(x) = 4(1.02)x; spreads at a rate of approximately 0.2% daily

<u>Solution:</u>

The weekly number of people infected would be:

f(x)=4(1.15)^x

7 days in a week, so daily number of people infected would be:

f(x)=4(1+r)^{7x}

To find daily rate, we set these 2 equations equal and solve for r:

4(1.15)^x=4(1+r)^{7x}\\1.15^x=(1+r)^{7x}\\1.15^x=((1+r)^7)^x\\1+r=1.02\\r=1-1.02=0.02

That is 0.02*100 = 2% daily

2nd answer choice is right.

8 0
3 years ago
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