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3 years ago

You have $60. You want to buy a pair of jeans and a shirt. The pair of jeans cost $27.

Mathematics

1 answer:

Volgvan3 years ago

8 0

Answer:

$18

Step-by-step explanation:

Buying the jeans for $27 leaves you with ($60 - $27), or $33.

Buying the shirt for s dollar leaves you with $15. To find s, the price of the shirt, you subtract $15 from $33: $18.

The shirt cost you $18.

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After completing the fraction division StartFraction 7 Over 3 EndFraction divided by StartFraction 2 Over 9 EndFraction, Bai use

max2010maxim [7]

The answer is

Letter D

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3 years ago

Read 2 more answers

Statuary Hall is an elliptical room in the United States Capitol in Washington, D.C. The room is also called the Whispering Gall

dalvyx [7]

Answer: a) $\frac{x^{2} }{2352.25 }$ + $\frac{y^{2} }{529}$ = 1

b) The distance of two foci is 85.4 feet

c) Area = 3502.67 square feet

Step-by-step explanation: a) An ellipse has the equation in the form of:

$\frac{x^{2} }{a^{2} }$ + $\frac{y^{2} }{b^{2} }$ = 1, where a is the horizontal axis and b is the vertical axis.

For the Statuary Hall, a = $\frac{97}{2}$ = 48.5 and b = $\frac{46}{2}$ = 23, so the equation will be

$\frac{x^{2} }{2352.25 }$ + $\frac{y^{2} }{529}$ = 1.

b) To determine the distance of the foci, we have to calculate 2c, where c is the distance between one focus and the center of the ellipse. To find c, as a, b and c create a triangle with a as hypotenuse:

$a^{2}$ = $b^{2} + c^{2}$

$c^{2} = a^{2} - b^{2}$

c = $\sqrt{48.5^{2} - 23^{2} }$

c = 42.7

The distance is 2c, so 2·42.7 = 85.4 feet.

The two foci are 85.4 feet apart.

c)The area of an ellipse is given by:

A = a.b.π

A = 48.5 · 23 · 3.14

A = 3502.67 ft²

The area of the floor room is 3502.67ft².

3 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

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

<em>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. </em>

This means that,

<em>Probability that at least one of them needs replacement at the first inspection = </em>

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