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4 years ago

if the formula for the perimeter of a rectangle is p=2l+2w, what is the formula for w in terms of p and l

Mathematics

1 answer:

aleksklad [387]4 years ago

3 0

Answer:

(p-2l)/2 = w

Step-by-step explanation:

p=2l+2w

We want to solve for w.

The first step is to subtract 2l from each side

p-2l=2l-2l+2w

p-2l=2w

Then we will divide each side by 2 to isolate w

(p-2l)/2 = 2w/2

(p-2l)/2 = w

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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

With a family bowling pass, families can bowl for $4 per game . The pass cost $10 per year. Use equation , a table and a graph t

Klio2033 [76]

Answer:

Part a) $a=4g+10$ (see the explanation)

Part b) see the explanation

Part c) The graph in the attached figure

Step-by-step explanation:

The complete question is

With a family bowling pass, families can bowl for $4 per game. The pass costs $10 per year. Use an equation, a table, and a graph to explain the relationship between the total amount of money spent on bowling in a year, a, and the number of games a family plays in a year, g. Part A Use words and an equation to represent this problem. Part B Create a table to show values for g and a. Part C Use the values from your table to draw a graph.

Part A) Use words and an equation to represent this problem

Let

a ----> the total amount of money spent on bowling in a year

g ---> the number of games a family plays in a year

we know that

The linear equation in slope intercept form is equal to

$a=mg+b$

where

m is the slope or unit rate

b is the a-intercept or initial value

In this problem we have

$m=\$4\ per\ game$

$b=\$10$

substitute

$a=4g+10$

Part b) Create a table to show values for g and a

Assume different values of g and calculate the corresponding values of a

For g=0 ----> $a=4(0)+10=\$10$

For g=1 ----> $a=4(1)+10=\$14$

For g=2 ----> $a=4(2)+10=\$18$

For g=3 ----> $a=4(3)+10=\$22$

For g=4 ----> $a=4(4)+10=\$26$

The table is

$\left[\begin{array}{ccc}g&a\\0&10\\1&14\\2&18\\3&22\\4&26\end{array}\right]$

Part c) Use the values from your table to draw a graph

we have the ordered pairs

$(0,10),(1,14),(2,18),(3,22),(4,26)$

Plot the ordered pairs and join them to graph the line

The graph in the attached figure

6 0

3 years ago

This is very confusing

drek231 [11]

Answer:

Step-by-step explanation:

6 0

3 years ago

To see how costly it would be for other people to compete a similar cycling tour, you decide to work out two averages and compar

Damm [24]

Group A

Money spent by Person 1 = £500

Money spent by Person 2 = £600

Money spent by Person 3 = £900

Money spent by Person 4 = £450

Sum of money spent by group A = £2,450

Average money spent by group A = $\frac{2,450}{4}$

⇒ Average money spent by group A = £612.5

Group B

Money spent by Person 1 = £700

Money spent by Person 2 = £500

Money spent by Person 3 = £680

Money spent by Person 4 = £500

Sum of money spent by group B = £2,380

Average money spent by group B = $\frac{2,380}{4}$

⇒ Average money spent by group B = £595

Hence, Group B had lower average spend.

4 0

3 years ago

A rectangular pyramid has a height of 8 meters. The base is 7 meters in length and 15 meters in width two different triangular c

vagabundo [1.1K]

Answer:

The difference in the areas of the cross section is 32 m²

Step-by-step explanation:

The given parameters are;

The height of the rectangular pyramid = 8 meters

The length of the base of the pyramid = 7 meters

The width of the base of the pyramid = 15 meters

Whereby triangular cross sections are formed through the vertex and perpendicular to the base, and to each other, we have;

The sides of the two triangles consists of the following;

1) Two slant height of the pyramid each

2) The two perpendicular lines joining the midpoints of the opposite sides of the base of the pyramid with length equal to the length of the adjacent side to the sides from which they are drawn which are 15 meters and 7 meters

3) The two lines and the corresponding slant height form triangles cross section which are perpendicular to each other.

the slant height, $h_l$ , is given as follows;

$h_l$ = √(8² + (15/2)²) ≈ 10.966

For the triangular cross section with base = 15 m

The area of the cross section = 1/2 × Base₁₅ × Height = 1/2 × 15 m × 8 m = 60 m²

For the triangular cross section with base = 7 m

The area of the cross section = 1/2 × Base₇ × Height = 1/2 × 7 m × 8 m = 28 m²

The difference in the areas of the cross section = 60 m² - 28 m² = 32 m².

5 0

3 years ago