Does the answer seem correct?

Francesca tried to evaluate an expression. Here is her work: 3(5)2–18÷3 = 3(25)–18÷3 = 75–18÷3 = 57÷3 = 19 Is Francesca's work c

hram777 [196]

Answer:

Nope. Moltiplication (and thus divisions) has to be done before any addition or subtractions, unless parenthesis indicate otherwise.

$3(5)^2 - 18\div 3 = 3(25) - 6 = 75-6=69$

5 0

2 years ago

Help! Which is the right one?

Olegator [25]

Answer:

it depends on the rest of the equation

Step-by-step explanation:

sss is used for using 3 sides to determine if the triangles are congruent, asa uses an angle then a side then an angle, sas uses a side then an angle then a side, ssa uses a side, then another side, then an angle

8 0

3 years ago

Christopher can paint the interior of his house in 15 hours. if he hires cynthia to help him they can do the same job together i

jenyasd209 [6]

If Christopher can paint his whole house in 15 hours, then he can get 1/15 of the job done in a single hour. If he hires Cynthia to help and they get the job done together (the sum of their efforts) in 9 hours, they can get 1/9 of the job done in a single hour. We are looking for how long Cynthia would take to do it on her own. Remember we are adding their efforts together and setting that equal to the total, so the equation is $\frac{1}{15}+\frac{1}{x}=\frac{1}{9}$ . What we are going to do here, what makes the most sense in solving for x, is to move the term with x in it to the other side of the equation and move the 1/9 over by subtraction. $\frac{1}{15}-\frac{1}{9}=-\frac{1}{x}$ . Of course before we can subtract those 2 fractions we need a common denominator, which happens to be 45: $\frac{3}{45}-\frac{5}{45}=-\frac{1}{x}$ and $-\frac{2}{45}=-\frac{1}{x}$ . We will cross multiply to get 2x = 45 and divide to find that it takes Cynthia 22.5 hours to do the job if she had to do it alone.

7 0

3 years ago

Pls help this is due soon pls pls

lana [24]

Answer:

1500

Step-by-step explanation:

All you have to do is multiple the powers together!! 15x100=1500

7 0

3 years ago

A market research firm supplies manufacturers with estimates of the retail sales of their products from samples of retail stores

KengaRu [80]

Answer:

The 95% confidence interval for the difference of means is (7.67, 16.33).

The estimate is Md = 12.

The standard error is sM_d = 2.176.

Step-by-step explanation:

We have to calculate a 95% confidence interval for the difference between means.

The sample 1 (this year's sales), of size n1=36 has a mean of 53 and a standard deviation of 12.

The sample 2 (last year's sales), of size n2=49 has a mean of 41 and a standard deviation of 6.

The difference between sample means is Md=12.

$M_d=M_1-M_2=53-41=12$

The estimated standard error of the difference between means is computed using the formula:

$s_{M_d}=\sqrt{\dfrac{\sigma_1^2}{n_1}+\dfrac{\sigma_2^2}{n_2}}=\sqrt{\dfrac{12^2}{36}+\dfrac{6^2}{49}}\\\\\\s_{M_d}=\sqrt{4+0.735}=\sqrt{4.735}=2.176$

The degrees of freedom are:

$df=n_1+n_2-1=36+49-2=83$

The critical t-value for a 95% confidence interval and 83 degrees of fredom is t=1.989.

The margin of error (MOE) can be calculated as:

$MOE=t \cdot s_{M_d}=1.989 \cdot 2.176=4.328$

Then, the lower and upper bounds of the confidence interval are:

$LL=M_d-t \cdot s_{M_d} = 12-4.328=7.67\\\\UL=M_d+t \cdot s_{M_d} = 12+4.328=16.33$

The 95% confidence interval for the difference of means is (7.67, 16.33).

7 0

3 years ago