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3 years ago

The model represents an equation. What value of X makes the equation true?

Mathematics

1 answer:

Anettt [7]3 years ago

8 0

Answer:

D. 3

Step-by-step explanation:

Assuming the model represents an equation, the following can be deduced:

On the left side of the equation, the model shows we have 3 "x's", and 6 "1's". Let this represent:

3x + 6

On the right side of the equation, we have 2 "x's" and 9 "1's". Let this represent:

2x + 9.

The model would represent the equation below:

$3x + 6 = 2x + 9$

Solve for x

$3x + 6 - 2x = 2x + 9 - 2x$ (Subtracting 2x from both sides of the equation)

$x + 6 = 9$

$x + 6 - 6 = 9 - 6$ (subtracting 6 from both sides of the equation)

$x = 3$

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A random sample of 180 microbiology students were asked how many science classes he or she was enrolled in August 1990. The resu

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Answer:

$z=\frac{1.83-1.94}{\sqrt{\frac{1.48^2}{180}+\frac{1.62^2}{180}}}}=-0.673$

$p_v =2*P(z$

Comparing the p value with the significance level given $\alpha=0.05$ we see that $p_v>\alpha$ so we can conclude that we FAIL to reject the null hypothesis, and a would NOT be a significant difference in the two means

Step-by-step explanation:

Data given and notation

$\bar X_{1}=1.83$ represent the mean in 1990

$\bar X_{2}=1.94$ represent the mean for 2005

$s_{1}=1.48$ represent the sample deviation for 1990

$s_{2}=1.62$ represent the sample standard deviation for 2005

$n_{1}=180$ sample size for 1990

$n_{2}=180$ sample size for 2005

t would represent the statistic (variable of interest)

$\alpha=0.05$ significance level provided

Develop the null and alternative hypotheses for this study?

We need to conduct a hypothesis in order to check if the means for the two groups are different, the system of hypothesis would be:

Null hypothesis: $\mu_{1}=\mu_{2}$

Alternative hypothesis: $\mu_{1} \neq \mu_{2}$

Since we don't know the population deviations for each group, for this case is better apply a t test to compare means, and the statistic is given by:

$z=\frac{\bar X_{1}-\bar X_{2}}{\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}}$ (1)

z-test: Is used to compare group means. Is one of the most common tests and is used to determine whether the means of two groups are equal to each other.

Calculate the value of the test statistic for this hypothesis testing.

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

$z=\frac{1.83-1.94}{\sqrt{\frac{1.48^2}{180}+\frac{1.62^2}{180}}}}=-0.673$

What is the p-value for this hypothesis test?

Since is a bilateral test the p value would be:

$p_v =2*P(z$

Based on the p-value, what is your conclusion?

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4 years ago

How many 3-digit even numbers are that begin with either 5 or 6?

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Answer: 100 3 digit even number that begin with either 5 or 6

Explanation:
Case 1:
A 3 digit that begin with 5 should be 500-599 so there are 100 numbers
But we are only finding even number
So 100/2 = 50 3-digit even number that begin with 5.

Case 2:
A 3 digit that begin 6 should have
600-699 and there are also 100 number including even and odd in total. Since we are only finding even number we get:
100/2 = 50 3-digit even number that begin with 6.

Plus both case together we get 50 3-digit even number that begin with 5 + 50 3-digit even number that begin with 6= 50 + 50 = 100

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4 years ago

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