Please Help ASAP!!!!!!!!!!!!

A construction worker bought several bottles of juice for three dollars at the convenient store. She paid for them with a $20 bi

Veronika [31]

20-3j=change she should receive.

5 0

4 years ago

Bill's chocolate bar is 69% cocoa. If the weight of the chocolate bar is 83 grams, how many grams of cocoa does it contain? Roun

Maurinko [17]

Answer:

Bill's bar has 57.3 grams of cocoa.

Step-by-step explanation:

The math part that your question is asking is: What is 69% of 83?

In order to use the percent 69% in a calculation, you need to change it to a decimal.

69% is 0.69

You move the decimal to the left, two places.

69% is 69.% If you don't see a decimal to start with and it is a whole number, then the decimal is starting on the right.

Move it two places to the left, you get

.69

Now MULTIPLY.

.69 × 83

= 57.27

ROUND your answer to the nearest tenth. That means only one digit to the right of the decimal.

57.27 rounds to 57.3

Bill's bar has 57.3 grams of cocoa.

8 0

2 years ago

A news item is spreading by word of mouth through a population of size 12,000 people. After t days, the number of people (in tho

Lilit [14]

Answer:

a) 2.303

b) $f'(t)=\frac{432e^{-0.48t}}{(1+75e^{-0.48t})^{2}}$

c) 1.3609

e) $\frac{dy}{dx}=0.04y(12-y)$

f) 4.5 thousand people(smaller)

7.5 thousand people (larger)

e) t=7.93 days (smaller)

t=10.06 days (larger)

g) 1.44

Step-by-step explanation:

The given function is $y=f(t)=\frac{12}{1+75e^{-0.48t}}$

To find how many thousand people have heard the news after 6 days, we substitute to get:

$f(6)=\frac{12}{1+75e^{-0.48*6}}=2.303$ thousands.

b) We rewrite to get: $f(t)=12(1+75e^{-0.48t})^{-1}$

We differentiate using the chain rule to obtain:

$f'(t)=-12(1+75e^{-0.48t})^{-2}\cdot 75e^{-0.48t}\cdot -0.48$

This simplifies to:

$f'(t)=432e^{-0.48t}(1+75e^{-0.48t})^{-2}$

We rewrite as positive index to get:

$f'(t)=\frac{432e^{-0.48t}}{(1+75e^{-0.48t})^{2}}$

c) To find the rate at which the news is spreading after 8 days, we substitute t=8 into $f'(t)=\frac{432e^{-0.48t}}{(1+75e^{-0.48t})^{2}}$ to get:

$f'(8)=\frac{432e^{-0.48\cdot 8}}{(1+75e^{-0.48\cdot 8})^{2}}=1.3609$

d) The solution to the logistic differential equation:

$\frac{dy}{dt}=ky(M-y)$

is

$y=\frac{M}{1+be^{-Mkt}}$

By comparison, M=12, and $Mk=0.48$

$12k=0.48\\k=0.04$

The differential equation is:

$\frac{dy}{dx}=0.04y(12-y)$

e) To how many people have heard the news when its rate of spread is 1.35 thousand per day, we equate the differential equation to 1.35 and so for t first.

$\frac{432e^{-0.48t}}{(1+75e^{-0.48t})^{2}}=1.35$

This gives us: t=10.06 ot t=7.93

We substitute the times into the function to get:

$f(7.93)=\frac{12}{1+75e^{-0.48\cdot7.93}}$ =4.5 thousand: smaller value

$f(10.06)=\frac{12}{1+75e^{-0.48\cdot10.06}}=7.5$ thousand: Larger value

f) The two times that the news is spreading at rate 1.35 thousand people per day are:

$t=7.93$ days: Smaller value

$t=10.06$ : Larger value

g) To find the fastest rate at which the news spread we take the second derivative and equate it to zero.

$f''(t)=0$

This corresponds to where the horizontal line is tangent to

$f'(t)=\frac{432e^{-0.48t}}{(1+75e^{-0.48t})^{2}}$

From the graph the point of tangency is:

(8.99,1.44)

Therefore the fastest rate at which the news spread is 1.44

7 0

3 years ago

Many states are carefully considering steps that would help them collect sales taxes on items purchased through the Internet. Ho

prisoha [69]

Answer:

96

Step-by-step explanation:

Step 1

Divide your confidence interval by 2. In this case the confidence is 95% = 0.095, so 0.095/2 = 0.0475

Step 2

Use either a z-score table or a computer to find the closest z-score for 0.0475 and you will find this value is 1.96

Step 3

Divide the margin error by 2. In this case, the margin error is 2%. When dividing this figure by 2, we get 1% = 0.01

Step 4

Divide the number obtained in Step 2 by the number obtained in Step 3 and square it

1.96/0.01 = 196 and 196 squared is 38,416

Step 5

As we do not now a proportion of people that purchase on line, we must assume this value is 50% = 0.5. Square this number and you get 0.25

Step 6

Multiply the number obtained in Step 5 by the number obtained in Step 4, round it to the nearest integer and this is an appropriate size of the sample.

38,416*0.25 = 9,604

6 0

4 years ago

81_ Evaluate 3! 6 336 6720 40,320

ella [17]

Answer:

6

Step-by-step explanation:

3!= 3(2)*1 = 6

6 0

3 years ago