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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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Answer:

f(x) = 2x² - 8x - 10.

This is a parabola open upward (since a>0) with an axis of symmetry = -b/2a:

a) axis of symmetry: x = -(-8)/(2*2) = 8/4 = 2. Then x = 2, which is the x component of the vertex

b) for x =  2, f(x) = f(2) = - 18 (component of y of the vertex)

c) VERTEX(2, - 18)

d) DISCRIMINENT: b² - 4.a.c = 64 - 4*2*(-10) = 144

Hope this helps! :)

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zheka24 [161]

Answer:

Probability = 0.12025

Step-by-step explanation:

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P (Am U At) = P (Am) + P (At) - P (Am ∩ At )

= 0.02 + 0.125 - 0.01

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P (Am' ∩ At') = 1 - P (Am U At)

P (Am' ∩ At')  = 1 - 0.135 = 0.865      {Person sees none ad}

Prob (Purchase) = Prob (Purchase with ad) + Prob (purchase without ad)

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P (P) = (0.25) (0.135) + (0.1) (0.865)

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3 years ago
135. sale price and 25percent of sale price what was the regular price
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Answer:

the regular price was 33.75

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Thus, the equation is y = (2/4)x +4

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3 years ago
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