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madam [21]
3 years ago
8

Does anyone know how to do this

Mathematics
2 answers:
zhenek [66]3 years ago
6 0
Tom's age: x 
Maria is twice as old as Tom sober age is 2x 

2x+x=30

3x=30

x=10 

Tom is 10 years old and Maria is 20 years old.
Julli [10]3 years ago
5 0
Maria = x
Tom = y

Use substitution
x+y=30
2y=x

2y+y=30
3y=30
y=10
Tom is 10 years old.

x+y=30

x+10=30
x=20
Maria is 20 years old.



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madam [21]
28 width each strip centimeters
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Which of the following expressions is equivalent to 32 ÷ 4• 4 ÷ 2 • 2?​
mel-nik [20]

Answer:

128

Step-by-step explanation:

32 ÷ 4• 4 ÷ 2 • 2

8 .4.2.2

128

6 0
3 years ago
How to find the product of (3y^2+ 2y + 2)(3y^2- 4y - 5)
Nastasia [14]

Answer:

= 9y^4 -6y^3 -17y^2 -18y -10

Step-by-step explanation:

(3y^2 + 2y + 2) x (3y^2 – 4y – 5)

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3 0
3 years ago
315 + 6x = 90 + 15x can anyone help with this? please
mario62 [17]

Answer:

315-90 = 15x-6x

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9x/225

x = 25

8 0
3 years ago
2. A marketing firm is trying to estimate the proportion of potential car buyers that would consider
Maurinko [17]

Answer:

a. The number of people that should be in the pilot study are 600 people

b. The point estimate is 0.62\overline 6

c. At 95% confidence level the true population proportion of potential car buyers of hybrid vehicle is between the confidence interval (0.588, 0.6654)

d. Two ways to reduce the margin of error are;

1) Reduce the confidence interval

2) Use a larger sample size

Step-by-step explanation:

a. The given parameters for the estimation of sample size is given as follows;

The margin of error for the confidence interval, E = 4% = 0.04

The confidence level = 95%

The sample size formula for a proportion as obtained from an online source is given as follows;

n = \dfrac{Z^2 \times P \times (1 - P)}{E^2}

Where, P is the estimated proportions of the desired statistic, therefore, we have for a new study, P = 0.5;

Z = The level of confidence at 95% = 1.96

n + The sample size

Therefore, we have;

n = \dfrac{1.96^2 \times 0.5 \times (1 - 0.5)}{0.04^2} = 600.25

Therefore, the number of people that should be in the pilot study in order to meet this goal at 95% confidence level is n = 600 people

b. The point estimate for the population proportion is the sample proportion  given as follows;

\hat p = \dfrac{x}{n}

Where;

x = The number of the statistic in the sample

n = The sample size

From the question, we have;

The number of potential car buyers, n = 600

The number of respondent in the sample that indicated that they would consider purchasing a hybrid, x = 376

Therefore, the point estimate, for the proportion of potential car buyers that would consider buying a hybrid vehicle, \hat p = 376/600 = 0.62\overline 6

c. The confidence interval for a proportion is given as follows

CI=\hat{p}\pm z\times \sqrt{\dfrac{\hat{p}(1-\hat{p})}{n}}

Therefore, we get;

CI=0.62 \overline 6\pm 1.96\times \sqrt{\dfrac{\hat{0.62 \overline 6}\cdot (1-\hat{0.62 \overline 6})}{600}}

C.I. ≈ 0.6267 ± 0.0387

The 95% confidence interval for the true population proportion of potential buyers of hybrid vehicle, C.I. =  (0.588, 0.6654)

d. The margin of error is given by the following formula;

MOE_\gamma = z_\gamma  \times \sqrt{\dfrac{\sigma ^2}{n} }

Where;

MOE_\gamma = Margin of error at a given level of confidence

z_\gamma = z-score

σ = The standard deviation

n = The sample size

Therefore, the margin error can be reduced by the following two ways;

1) Reducing the confidence interval and therefore, the z-score

2) Increasing the sample size

6 0
2 years ago
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