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2 years ago

1. Sarah has an average of 92.5 for her 3 science tests. What does she need to make on the 4th test to get a 94% average.

1 answer:

4 0

1) set up a problem
you know you want to get an avg of 94 but how do you do avg in the first place. you add up the numbers then divde by the total number of numbers used lol

so $\frac{92.5+x}{2}=94$
92.5 is the avg number for the last 3 tests
"x" is the 4th test score which we want to find out
"2" is the total number of numbers being added together

so now lets get x to one side

92.5+ x=94*2 (multiply 2 to both sides)
92.5+x=188
x=188-92.5 (subtract 92.5 from both sides)
x= 95.5 this is the score she need to make to avg 94%

2) you can draw a tree diagram. for example Flower1 branches off into 3 diff greens and then each of those greens branch off into 2 for with or with babies breath.

or you can simple multiply 4*3*2. you can do this because all choices are included with no restriction

your total number of options is 24

You might be interested in

El producto de dos números consecutivos es 552 cuáles son esos números?

lara31 [8.8K]

Answer: 23 y 24 ( ó -23 y -24)

Step-by-step explanation:

Dos números consecutivos se escriben como:

n y (n + 1)

done n es un numero entero.

Entonces "El producto de dos números consecutivos es 552"

Se escribe como:

n*(n + 1) = 552

n^2 + n = 552

n^2 + n - 552 = 0

Tenemos una cuadrática, las posibles soluciones son obtenidas con la formula de Bhaskara.

$n = \frac{-1 +- \sqrt{1^2 - 4*1*(-552)} }{2} = \frac{-1 +- 47}{2}$

Las dos soluciones son.

n = (-1 - 47)/2 = -48/2 = -24

n = (-1 + 47)/2 = 46/2 = 23

Si tomamos la primer solución, n = -24

Entonces los dos números consecutivos son:

n = -24

(n + 1) = -23

Si n = 23 entonces

n + 1 = 24

Lo cual tiene sentido, por que lo único que cambia son los signos, los cuales se cancelarían en la multiplicación.

7 0

2 years ago

Among a simple random sample of 331 American adults who do not have a four-year college degree and are not currently enrolled in

Hitman42 [59]

Answer:

(1) Therefore, a 90% confidence interval for the proportion of Americans who decide to not go to college because they cannot afford it is [0.4348, 0.5252].

(2) We can be 90% confident that the proportion of Americans who choose not to go to college because they cannot afford it is contained within our confidence interval

(3) A survey should include at least 3002 people if we wanted the margin of error for the 90% confidence level to be about 1.5%.

Step-by-step explanation:

We are given that a simple random sample of 331 American adults who do not have a four-year college degree and are not currently enrolled in school, 48% said they decided not to go to college because they could not afford school.

Firstly, the pivotal quantity for finding the confidence interval for the population proportion is given by;

P.Q. = $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ~ N(0,1)

where, $\hat p$ = sample proportion of Americans who decide to not go to college = 48%

n = sample of American adults = 331

p = population proportion of Americans who decide to not go to

college because they cannot afford it

Here for constructing a 90% confidence interval we have used a One-sample z-test for proportions.

So, 90% confidence interval for the population proportion, p is ;

P(-1.645 < N(0,1) < 1.645) = 0.90 {As the critical value of z at 5% level

of significance are -1.645 & 1.645}

P(-1.645 < $\frac{\hat p-p}{\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < 1.645) = 0.90

P( $-1.645 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < $\hat p-p$ < $1.645 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ) = 0.90

P( $\hat p-1.645 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ < p < $\hat p+1.645 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ) = 0.90

90% confidence interval for p = [ $\hat p-1.645 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ , $\hat p+1.645 \times {\sqrt{\frac{\hat p(1-\hat p)}{n} } }$ ]

= [ $0.48 -1.96 \times {\sqrt{\frac{0.48(1-0.48)}{331} } }$ , $0.48 +1.96 \times {\sqrt{\frac{0.48(1-0.48)}{331} } }$ ]

= [0.4348, 0.5252]

(1) Therefore, a 90% confidence interval for the proportion of Americans who decide to not go to college because they cannot afford it is [0.4348, 0.5252].

(2) The interpretation of the above confidence interval is that we can be 90% confident that the proportion of Americans who choose not to go to college because they cannot afford it is contained within our confidence interval.

3) Now, it is given that we wanted the margin of error for the 90% confidence level to be about 1.5%.

So, the margin of error = $Z_(_\frac{\alpha}{2}_) \times \sqrt{\frac{\hat p(1-\hat p)}{n} }$

$0.015 = 1.645 \times \sqrt{\frac{0.48(1-0.48)}{n} }$

$\sqrt{n} = \frac{1.645 \times \sqrt{0.48 \times 0.52} }{0.015}$

$\sqrt{n}$ = 54.79

n = $54.79^{2}$

n = 3001.88 ≈ 3002

Hence, a survey should include at least 3002 people if we wanted the margin of error for the 90% confidence level to be about 1.5%.

5 0

2 years ago

The formula that relates the length of a ladder, L, that leans against a wall with distance d from the base of the wall and the

Ulleksa [173]

Answer:

Step-by-step explanation:

The formula that relates the length of a ladder, L, that leans against a wall with distance d from the base of the wall and the height h that the ladder reaches up the wall is L = StartRoot d squared + h squared EndRoot. What height on the wall will a 15-foot ladder reach if it is placed 3.5 feet from the base of a wall?

L = √d² + h²

4 0

1 year ago

Read 2 more answers

t takes Dariya 35 seconds to download 5 songs from the Internet. How can the number of seconds it would take Dariya to download

Vitek1552 [10]

She would be able to download 49 at this rate.
Because 5/35 =7/n which would then =245/5 which equals 49

8 0

2 years ago

Read 3 more answers

Is the statement "Two matrices are row equivalent if they have the same number of rows" true or false? Explain. A. True, because

vlabodo [156]

Answer: The answer is (C).

Step-by-step explanation: The given statement is - "Two matrices are row equivalent if they have the same number of rows". We are to explain whether the statement is true or false.

What are row equivalent matrices? The answer to this question is -

Two matrices are said to be row equivalent if one of the matrices can be obtained from the other by applying a number of elementary row operations. Or, we can say two matrices of same order are row equivalent if they have same row space.

Thus, the correct option is (C).

7 0

2 years ago