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BabaBlast [244]

2 years ago

10

Jason's business computers need servicing. The expression 81x + 108 represents a contractor's total charges in dollars for fixin

g the problem. The expression 103x + 64 represents an electronic store's total charges in dollars for the same work. In both expressions, x is the number of hours it took to complete the job.

1 answer:

kolbaska11 [484]2 years ago

8 0

Answer:

2 hours

Step-by-step explanation:

Given

$Contractor: 81x + 108$

$Electronic\ Store: 103x + 64$

Required

Determine the hours when the charges are the same

To do this, we simply equate both expressions:

$Contractor = Electronic\ Store$

$81x + 108 = 103x + 64$

Collect Like Terms

$81x - 103x = 64 - 108$

$-22x = -44$

Divide both sides by -22

$x =2$

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You are building a toothpick fort for class. Each wall must be 1 1⁄3 feet long. Each toothpick is 2 inches long. How many toothp

Mariana [72]

Answer: 68/67.8 toothpicks

Step-by-step explanation

first convert how many inches 11.3 feet is

11.3 = 135.6 inches

so after you get your number you get your calculator and divide it by how many inches the toothpicks are

135.6 ÷ 2= 67.8

then to get a solid answer you would round it to a whole number

67.8--> 68

so you ether say the rounded number or you cut .2 inches off the last toothpick

(also im not sure if its 11.3ft or 113ft so if so then take away the decimal and do the same math, you'll end up with 678 toothpicks)

6 0

3 years ago

Solve this inequality for x. 81-1 1/5 x <55

katen-ka-za [31]

Answer:

A. x > 21 2/3

Step-by-step explanation:

x is greater than 21 and two thirds

i did the math :]

4 0

3 years ago

Can someone help me with this? look at picture

nika2105 [10]

Answer:

19 (using "3.14" as pi)

18.99036781...(using pi button)

Step-by-step explanation:

Formula: C=dπ

so, (59.66)=dπ

you would divide circumference (C) by pi which will get you the answers above :)

hope this helped

7 0

3 years ago

SAT scores are normed so that, in any year, the mean of the verbal or math test should be 500 and the standard deviation 100. as

vovangra [49]

Answer:

a) $P(X>625)=P(\frac{X-\mu}{\sigma}>\frac{625-\mu}{\sigma})=P(Z>\frac{625-500}{100})=P(Z>1.25)$

$P(Z>1.25)=1-P(Z$

b) $P(400$

$P(-1$

$P(-1$

c) $z=-0.842$

And if we solve for a we got

$a=500 -0.842*100=415.8$

So the value of height that separates the bottom 20% of data from the top 80% is 415.8.

Step-by-step explanation:

Previous concepts

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

The Z-score is "a numerical measurement used in statistics of a value's relationship to the mean (average) of a group of values, measured in terms of standard deviations from the mean".

Part a

Let X the random variable that represent the SAT scores of a population, and for this case we know the distribution for X is given by:

$X \sim N(500,100)$

Where $\mu=500$ and $\sigma=100$

We are interested on this probability

$P(X>625)$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(X>625)=P(\frac{X-\mu}{\sigma}>\frac{625-\mu}{\sigma})=P(Z>\frac{625-500}{100})=P(Z>1.25)$

And we can find this probability using the complement rule and with the normal standard table or excel:

$P(Z>1.25)=1-P(Z$

Part b

We are interested on this probability

$P(400$

And the best way to solve this problem is using the normal standard distribution and the z score given by:

$z=\frac{x-\mu}{\sigma}$

If we apply this formula to our probability we got this:

$P(400$

And we can find this probability with this difference:

$P(-1$

And in order to find these probabilities we can find tables for the normal standard distribution, excel or a calculator.

$P(-1$

Part c

For this part we want to find a value a, such that we satisfy this condition:

$P(X>a)=0.8$ (a)

$P(X$ (b)

Both conditions are equivalent on this case. We can use the z score again in order to find the value a.

As we can see on the figure attached the z value that satisfy the condition with 0.2 of the area on the left and 0.8 of the area on the right it's z=-0.842. On this case P(Z<-0.842)=0.2 and P(Z>-0.842)=0.8

If we use condition (b) from previous we have this:

$P(X$

$P(z$

But we know which value of z satisfy the previous equation so then we can do this:

$z=-0.842$

And if we solve for a we got

$a=500 -0.842*100=415.8$

So the value of height that separates the bottom 20% of data from the top 80% is 415.8.

8 0

3 years ago

Wittaler [7]

Answer:

See below

Step-by-step explanation:

Use the formulae directly

For a cone, with base radius = r and height = h, here are the related formula

$\textrm{Slant height l} = \sqrt{r^2 + h^2}$ (1)

$\textrm{Lateral surface area} = \pi r l$

$\textrm {Base area} = \pi r^2$

$\textrm { Total Surface Area SA} = \textrm{Base Area + Lateral Area} = \pi r^2 + \pi rl = \pi r(r + l)$ (2)

$\textrm{Volume V = } (1/3) \pi r^2h$ (3)

Therefore directly plugging in the numbers in the above equations:

Note:

l = slant height in cm
SA = total surface area in sqcm
V = Volume in cubic cm

Figure(a)

r = 4, h = 8

$\textrm{l} = \sqrt{4^2 + 8^2} =\sqrt{80} = 8.944 \\\textrm{SA} = 4\pi(4 + 8.944) = 4\pi(12.944) = 162.66\\\textrm{V} = (1/3)\pi(4^2)(8) = 134.04$

Figure(b)

r = 7, h =15

$\textrm{l} = \sqrt{7^2 + 15^2} =\sqrt{274} = 16.55$

$\textrm{SA} = 7\pi(7 + 16.55) = 517.89$

Figure (c)

r = 5, l = 8

$h = \sqrt{l^2 - r^2} = \sqrt{8^2 - 5^2} = \sqrt{39} = 6.245\\SA = \textrm{SA} = 5\pi(5 + 8) = 204.2\\V = (1/3)\pi(5^2)(6.245) = 163.5$

6 0

2 years ago