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3 years ago

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Mathematics

2 answers:

sashaice [31]3 years ago

8 0

Answer:

1) Expression

2) Equation

3) Equation

4) Expression

Step-by-step explanation:

An equation always contains an equal sign, so in this case, if it doesn't contain an equal sign, it's an expression.

For 2 and 3, you can see that there is an equal sign, but for 1 and 4, there is not.

Therefore, 1 and 4 are expressions and 2 and 3 are equations.

I hope this helped.

Marat540 [252]3 years ago

7 0

5x+2(x+3) is an expression

5x=2(x+3) is an equation

8m-3m+5=16 is an equation

8m-3m+5-16 is an expression

An equation always and I mean ALWAYS uses a = sign.

An expression is a combination of numbers and variables and symbols.

Hope that's useful

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If a is the set of all integers choose the set B that will make the following statement false

Tju [1.3M]

Answer:

Try the 2nd one

Step-by-step explanation:

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3 years ago

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The sum of a number and 5 times a second number is represented by the equation a+5b=19 . The sum of half of the first number and

TiliK225 [7]

Here you have a system of 2 equations and 2 unknowns. An easy way to solve this type is to isolate one of the variables.

12a + 2b = 8
2b = 8 - 12a
b =
$b = \frac{8 - 12a }{2}$
b = 4 - 6a

Now plug 4 - 6a into equation 1 to solve for a.

a + 5(4 - 6a) = 19

a + 20 - 30a = 19

-29a = -1

a = 1/29 (answer)

Now plug a into the equation for b

b= 4 - 6(1/29)

b= 110/29 (answer)

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3 years ago

The following 5 questions are based on this information: An economist claims that average weekly food expenditure of households

liq [111]

Answer:

Null hypothesis: $\mu_{1}-\mu_{0}\leq 0$

Alternative hypothesis: $\mu_{1}-\mu_{2}>0$

$SE=\sqrt{\frac{12.5^2}{35}+\frac{9.25^2}{30}}=2.705$

b) 2.70

$t=\frac{(164-159)-0}{\sqrt{\frac{12.5^2}{35}+\frac{9.25^2}{30}}}=1.850$

b. 1.85

$p_v =P(Z>1.85)=0.032$

b. 0.03

a. We can reject H(0) in favor of H(a)

Step-by-step explanation:

Data given and notation

$\bar X_{1}=164$ represent the mean for the sample 1

$\bar X_{2}=159$ represent the mean for the sample 2

$\sigma_{1}=12.5$ represent the population standard deviation for the sample 1

$s_{2}=9.25$ represent the population standard deviation for the sample B2

$n_{1}=35$ sample size selected 1

$n_{2}=30$ sample size selected 2

$\alpha=0.05$ represent the significance level for the hypothesis test.

t would represent the statistic (variable of interest)

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

State the null and alternative hypotheses.

We need to conduct a hypothesis in order to check if the expenditure of households in City 1 is more than that of households in City 2, the system of hypothesis would be:

Null hypothesis: $\mu_{1}-\mu_{0}\leq 0$

Alternative hypothesis: $\mu_{1}-\mu_{2}>0$

We know the population deviations, so for this case is better apply a z test to compare means, and the statistic is given by:

$z=\frac{(\bar X_{1}-\bar X_{2})-0}{\sqrt{\frac{\sigma^2_{1}}{n_{1}}+\frac{\sigma^2_{2}}{n_{2}}}}$ (1)

t-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".

Standard error

The standard error on this case is given by:

$SE=\sqrt{\frac{s^2_{1}}{n_{1}}+\frac{s^2_{2}}{n_{2}}}$

Replacing the values that we have we got:

$SE=\sqrt{\frac{12.5^2}{35}+\frac{9.25^2}{30}}=2.705$

b. 2.70

Calculate the statistic

We can replace in formula (1) the info given like this:

$t=\frac{(164-159)-0}{\sqrt{\frac{12.5^2}{35}+\frac{9.25^2}{30}}}=1.850$

P-value

Since is a one side right tailed test the p value would be:

$p_v =P(Z>1.85)=0.032$

b. 0.03

Conclusion

If we compare the p value and the significance level given $\alpha=0.05$ we see that $p_v$ so we can conclude that we have enough evidence to reject the null hypothesis.

a. We can reject H(0) in favor of H(a)

4 0

3 years ago

Two joggers run 8 miles north and then 5 miles west. What is the shortest

Verdich [7]

The shortest distance they have to travel to return to their starting point is 9.4 miles.

Explanation

The joggers run 8 mile north and then runs 5 miles west. we have to calculate the shortest distance they have to travel to return to their starting point.

The distance traveled north and west respectively makes the height and base of a right angled triangle.

to find the shortest distance to the starting point, the hypotenuse has to be determined.

height h=8 miles

base b=5 miles

using pythagoras theorem

$b^2+h^2=H^2\\5^2+8^2=H^2\\25+64=H^2\\89=H^2\\\\H=\sqrt{89} =9.433=9.4 miles$