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3 years ago

Lynette has a metal doorstop with the dimensions shown.

Mathematics

1 answer:

Cerrena [4.2K]3 years ago

7 0

Volume = 105in³

Mass = 871.5g

To find the volume of the metal we can find the area of a base, and multiply it by the prism's width.

The base is 30cm in area, and the width is 3.5cm, which makes the volume 105in³

The mass of the doorstop can be found by just multiplying the grams per cubic centimeter by the volume, which would be 871.5g

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Gabriel brings 25 cupcakes to share with his classmates at school. At the end of the day, he has 3 cupcakes remaining. What perc

swat32

Answer:88%

Step-by-step explanation:

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3 years ago

Read 2 more answers

2. The pool maintenance man forgot to bring his logarithmic charts, and he needs to raise

rusak2 [61]

Answer:

hey have made this a little more confusing than it has to be. Usually we use H+ in chemistry instead of t, but you can also use X, Y if it's easier where Y = -log(X) where X= hydronium and Y = pH.

Which also means Y=p(t) and X = t.

To graph this, I would suggest using values for X like 0.1, 0.2, 0.5, 0.7, 1.0, 1.5, or similar numbers. Then use your calculator to calculate Y values for each of these X values and plot them. You can also use a spreadsheet. If you have Excel I can help you to use it. Either way you can then use your graph to answer the questions in part 1 where Y = 0 and Y=1 and just read off the X values.

Part 2 is worded badly. It's ambiguous to say "raised by 0.5" since if you raise hydronium (= X) by 0.5, the change in pH (=Y) will vary depending on where you start. They meant "raise to 0.5", though they do say this at the end of the question. Anyway, you can easily read it off your graph using 0.5 as the X value.

Now to set up the exponential function this is much easier than it sounds. Just remember that a logarithm is the inverse of an exponent so they cancel each other out: As an example log(10X) = X.

So applying here, just take this equation Y = -log(X) and raise 10 to both sides of the equation:

10Y = 10-log(X) which gives you 10Y = 1/X or more usefully X = 10-Y where again X= hydronium and Y = pH

Part 3, these questions actually have no relationship to anything in chemical reality, but are just exercises to see if you can manipulate the graph and function. But they do illustrate at least one interesting point. Note that in the equation

X = 10-Y

X can never =0. This makes sense since there is nothing you can raise 10 to that will make it zero. It also makes sense chemically since in water you can never have zero hydronium. Similarly using the other form

Y = -log(X)

You know X can also never be zero since you can't have log(0).

Now when they ask for a "Y intercept" they are asking for when X=0 which as stated is never in the above case. However when you transform the equation the ways they want you to, then maybe sometimes you can:

So for p(t) + 1 that really means Y = -log(x) + 1. Still here you can not have a Y intercept (X can't =0) since you would still have log(0) which is forbidden.

But p(t+1) really means Y = -log(X+1). Here of course X can be zero since that just gives you log(1). So you have a Y-intercept.

I'll leave it for you to figure out the third one, the question being if you set X=0, will you get log(0)? If so, that's forbidden. If not, you will have a Y intercept.

5 0

2 years ago

The vertex angle of an isosceles triangle measures 42°. A base angle in the triangle has a measure given by

Dmitry_Shevchenko [17]

Answer:

x=33

Each base angle measures 69 degrees

Step-by-step explanation:

the 2 base angles are equal so the measure of 1 base angle = (180 - 42) / 2

= 69 degrees

2x + 3 = 69

2x = 66

x = 33

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3 years ago

The Wall Street Journal reports that 33% of taxpayers with adjusted gross incomes between $30,000 and $60,000 itemized deduction

Len [333]

Answer:

(a) n : 20 50 100 500

P (-200 < X - μ < 200) : 0.2886 0.4444 0.5954 0.9376

(b) The correct option is (b).

Step-by-step explanation:

Let the random variable X represent the amount of deductions for taxpayers with adjusted gross incomes between $30,000 and $60,000 itemized deductions on their federal income tax return.

The mean amount of deductions is, μ = $16,642 and standard deviation is, σ = $2,400.

Assuming that the random variable X follows a normal distribution.

(a)

Compute the probability that a sample of taxpayers from this income group who have itemized deductions will show a sample mean within $200 of the population mean as follows:

For a sample size of n = 20

$P(\mu-200$

$=P(-0.37$

For a sample size of n = 50

$P(\mu-200$

$=P(-0.59$

For a sample size of n = 100

$P(\mu-200$

$=P(-0.83$

For a sample size of n = 500

$P(\mu-200$

$=P(-1.86$

n : 20 50 100 500

P (-200 < X - μ < 200) : 0.2886 0.4444 0.5954 0.9376

(b)

The law of large numbers, in probability concept, states that as we increase the sample size, the mean of the sample ( $\bar x$ ) approaches the whole population mean ( $\mu_{x}$ ).

Consider the probabilities computed in part (a).

As the sample size increases from 20 to 500 the probability that the sample mean is within $200 of the population mean gets closer to 1.

So, a larger sample increases the probability that the sample mean will be within a specified distance of the population mean.

Thus, the correct option is (b).

8 0

3 years ago

Which of the following is a polynomial with rootsnegative square root of 5, square root of 5, and 3

Scrat [10]

Answer:

P(x) = x³ - 3x² - 5x + 15

Step-by-step explanation:

∵ The roots of the polynomial are -√5 , √5 , 3

∴ The polynomial has 3 factors:

(x - √5) , (x + √5) , (x - 3)

∴ P(x) = (x - √5)(x + √5)(x - 3)

= (x² + √5x - √5x - 5)(x - 3)

= (x² - 5)(x - 3) = x³ - 3x² - 5x + 15

∴ P(x) = x³ - 3x² - 5x + 15

3 0

3 years ago