Evaluate c−d if c=11 and d=−3 .

Casey can buy 3 sandwiches and 5 cups of coffee for $26. Eric can buy 4 sandwiches and 2 cups of coffee for $23. How much does o

dolphi86 [110]

Let's identify what we are looking for in terms of variables. Sandwiches are s and coffee is c. Casey buys 3 sandwiches, which is represented then by 3s, and 5 cups of coffee, which is represented by 5c. Those all put together on one bill comes to 26. So Casey's equation for his purchases is 3s + 5c = 26. Eric buys 4 sandwiches, 4s, and 2 cups of coffee, 2c, and his total purchase was 23. Eric's equation for his purchases then is 4s + 2c = 23. In order to solve for c, the cost of a cup of coffee, we need to multiply both of those bolded equations by some factor to eliminate the s's. The coefficients on the s terms are 4 and 3. 4 and 3 both go into 12 evenly, so we will multiply the first bolded equation by 4 and the second one by -3 so the s terms cancel out. 4[3s + 5c = 26] means that 12s + 20c = 104. Multiplying the second bolded equation by -3: -3[4s + 2c = 23] means that -12s - 6c = -69. The s terms cancel because 12s - 12s = 0s. We are left with a system of equations that just contain one unknown now, which is c, what we are looking to solve for. 20c = 104 and -6c = -69. Adding those together by the method of elimination (which is what we've been doing all this time), 14c = 35. That means that c = 2.5 and a cup of coffee is $2.50. There you go!

8 0

3 years ago

regina bought fruit for her family. she bought 3 1/2 pounds of oranges and 4 and 3/4 pounds of peaches. if she used all bit 1 3/

jeka94

First, you would have to combine 3 1/2 and 4 3/4 pounds. That would be 8 and 1/4 lbs. If she used all but 1 3/8 lbs, you would have to do 8 1/4 minus 1 3/8. That means she used 7 1/8 lbs of fruit.

The equation would be 3/ 12 + 4 3/4 = 8 1/4 - 1/38 = 7 1/8.

8 0

3 years ago

Read 2 more answers

Which of these expressions shows like terms?

Natasha_Volkova [10]

Answer:

C

Step-by-step explanation:

2x+3x Have the same variable. Therefore they both have like terms

6 0

3 years ago

A well-known brokerage firm executive claimed that at least 41 % of investors are currently confident of meeting their investmen

atroni [7]

Answer:

$z=\frac{0.398 -0.41}{\sqrt{\frac{0.41(1-0.41)}{88}}}=-0.229$

Step-by-step explanation:

1) Data given and notation n

n=88 represent the random sample taken

X=35 represent the adults that said they are confident of meeting their goals

$\hat p=\frac{35}{88}=0.398$ estimated proportion of adults that said they are confident of meeting their goals

$p_o=0.41$ is the value that we want to test

$\alpha$ represent the significance level

z would represent the statistic (variable of interest)

$p_v$ represent the p value (variable of interest)

2) Concepts and formulas to use

We need to conduct a hypothesis in order to test the claim that that at least 41 % of investors are currently confident of meeting their investment goals.:

Null hypothesis: $p=0.41$

Alternative hypothesis: $p < 0.41$

When we conduct a proportion test we need to use the z statisitc, and the is given by:

$z=\frac{\hat p -p_o}{\sqrt{\frac{p_o (1-p_o)}{n}}}$ (1)

The One-Sample Proportion Test is used to assess whether a population proportion $\hat p$ is significantly different from a hypothesized value $p_o$ .

3) Calculate the statistic

Since we have all the info requires we can replace in formula (1) like this:

$z=\frac{0.398 -0.41}{\sqrt{\frac{0.41(1-0.41)}{88}}}=-0.229$

4) Statistical decision

It's important to refresh the p value method or p value approach . "This methos is about determining "likely" or "unlikely" by determining the probability assuming the null hypothesis were true of observing a more extreme test statistic in the direction of the alternative hypothesis than the one observed". Or in other words is just a method to have an statistical decision to fail to reject or reject the null hypothesis.

The significance level is not provided, but we can assume $\alpha=0.05$ . The next step would be calculate the p value for this test.

Since is a unilateral test the p value would be:

$p_v =P(z$

Using the p value obtained and the significance level assumed $\alpha=0.05$ we have $p_v>\alpha$ so we can conclude that we have enough evidence to FAIL to reject the null hypothesis, and we can said that at 5% of significance the proportion of of investors that are currently confident of meeting their investment goals is not significantly lower than 0.41 or 41%.

4 0

3 years ago

Starting at an initial height of 364 feet, an object is projected

Lana71 [14]

Step-by-step explanation:

4.5 s, 324 ft

Explanation:

The object is projected upward with an initial velocity of

v_0 = 144 ft/sv

0

=144ft/s

The equation that describes its height at time t is

s(t) = -16t^2 + 144 ts(t)=−16t

2

+144t (1)

where t, the time, is measured in seconds.

In order to find the time it takes for the object to reach the maximum height, we must find an expression for its velocity at time t, which can be found by calculating the derivative of the position, s(t):

v(t) = s'(t) = -32t +144v(t)=s

′

(t)=−32t+144 (2)

At the maximum heigth, the vertical velocity is zero:

v(t) = 0

Substituting into the equation above, we find the corresponding time at which the object reaches the maximum height:

\begin{gathered}0=-32t+144\\t=\frac{144}{32}=4.5 s\end{gathered}

0=−32t+144

t=

32

144

=4.5s

And by substituting this value into eq.(1), we also find the maximum height:

s(t) = -16(4.5)^2+144(4.5)=324 fts(t)=−16(4.5)

2

+144(4.5)=324ft

<h3>used this way i even don't know sorry:))</h3>

7 0

2 years ago