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2 years ago

Express cos K as a fraction in simplest terms.

Mathematics

1 answer:

nata0808 [166]2 years ago

4 0

Answer:

4/5

Step-by-step explanation:

In a right triangle such as this one

cos (angle) = adjacent leg / hypotenuse

cos(k) = KL / 15

You will need to find the leg length KL using Pythagorean Theorem

15^2 = 9^2 + (KL)^2 KL = 12

then cos k = 12/15 = 4/5

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6=−w8 how can i solve this

Vaselesa [24]

Divide 6 by -8 to get the variable alone!
6/-8 < division< equation

4 0

3 years ago

The life of a red bulb used in a traffic signal can be modeled using an exponential distribution with an average life of 24 mont

BartSMP [9]

Answer:

See steps below

Step-by-step explanation:

Let X be the random variable that measures the lifespan of a bulb.

If the random variable X is exponentially distributed and X has an average value of 24 month, then its probability density function is

$\bf f(x)=\frac{1}{24}e^{-x/24}\;(x\geq 0)$

and its cumulative distribution function (CDF) is

$\bf P(X\leq t)=\int_{0}^{t} f(x)dx=1-e^{-t/24}$

• What is probability that the red bulb will need to be replaced at the first inspection?

The probability that the bulb fails the first year is

$\bf P(X\leq 12)=1-e^{-12/24}=1-e^{-0.5}=0.39347$

• If the bulb is in good condition at the end of 18 months, what is the probability that the bulb will be in good condition at the end of 24 months?

Let A and B be the events,

A = “The bulb will last at least 24 months”

B = “The bulb will last at least 18 months”

We want to find P(A | B).

By definition P(A | B) = P(A∩B)P(B)

but B⊂A, so A∩B = B and

$\bf P(A | B) = P(B)P(B) = (P(B))^2$

We have

$\bf P(B)=P(X>18)=1-P(X\leq 18)=1-(1-e^{-18/24})=e^{-3/4}=0.47237$

hence,

$\bf P(A | B)=(P(B))^2=(0.47237)^2=0.22313$

• If the signal has six red bulbs, what is the probability that at least one of them needs replacement at the first inspection? Assume distribution of lifetime of each bulb is independent

If the distribution of lifetime of each bulb is independent, then we have here a binomial distribution of six trials with probability of “success” (one bulb needs replacement at the first inspection) p = 0.39347

Now the probability that exactly k bulbs need replacement is

$\bf \binom{6}{k}(0.39347)^k(1-0.39347)^{6-k}$

Probability that at least one of them needs replacement at the first inspection = 1- probability that none of them needs replacement at the first inspection.

This means that,

Probability that at least one of them needs replacement at the first inspection =

$\bf 1-\binom{6}{0}(0.39347)^0(1-0.39347)^{6}=1-(0.60653)^6=0.95021$

5 0

3 years ago

Kathi's order at the diner cost $12.75. She had to pay 6% tax on the bill. How much is her tax?

Talja [164]

$\begin{array}{|c|ll} \cline{1-1} \textit{a\% of b}\\ \cline{1-1} \\ \left( \cfrac{a}{100} \right)\cdot b \\\\ \cline{1-1} \end{array}~\hspace{5em}\stackrel{\textit{6\% of 12.75}}{\left( \cfrac{6}{100} \right)12.75}\implies 0.765~~\approx 0.77~~\textit{about 77 cents}$

3 0

3 years ago

I need help with both problems. Which one is true or false and why

stepladder [879]

The first equation can be simplified down to 3 and -\frac{3}{2}[/tex]. Therefore, ">" is correct.

The second equation can be simplified down to 12 and 6.25. Therefore, "<" is incorrect. It should be ">".

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3 years ago

Find the distance traveled by a car moving at an average speed of 40 miles per hour 3 hours.

Grace [21]

Answer: 120 miles traveled

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3 years ago