!Need answer quickly!

What number is equal to 2.8 - 4 ÷ 4? 02 03 O 14 O 15

VARVARA [1.3K]

Answer:

1.8

General Formulas and Concepts:

Pre-Algebra

Order of Operations: BPEMDAS

Brackets
Parenthesis
Exponents
Multiplication
Division
Addition
Subtraction

Left to Right

Step-by-step explanation:

Step 1: Define

2.8 - 4 ÷ 4

Step 2: Evaluate

Division: 2.8 - 1
Subtraction: 1.8

8 0

3 years ago

Solve for y: 10x=1000 A) y=-100 B) y=100 C) y=10 D) y=-10

prohojiy [21]

$\text {Hey! Let's Solve this Equation!}$

$\text {The Only Step is to Divide 10:}$

$\text {10y/10=1000/10}$

$\text {Your Answer would be:}$

$\fbox {y=100}$

$\text {Note: When dividing a number by 10 all you gotta do is remove a 0}$ $\text { when it comes to dividing numbers like 1000}$

$\text {Best of Luck!}$

8 0

2 years ago

Read 2 more answers

In a large midwestern university (the class of entering freshmen is 6000 or more students), an SRS of 100 entering freshmen in 1

Serga [27]

Answer:

The p-value of the test is 0.0228, which is less than the standard significance level of 0.05, which means that there is evidence that the proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced.

Step-by-step explanation:

Before solving this question, we need to understand the central limit theorem and subtraction of normal variables.

Central Limit Theorem

The Central Limit Theorem establishes that, for a normally distributed random variable X, with mean $\mu$ and standard deviation $\sigma$ , the sampling distribution of the sample means with size n can be approximated to a normal distribution with mean $\mu$ and standard deviation $s = \frac{\sigma}{\sqrt{n}}$ .

For a skewed variable, the Central Limit Theorem can also be applied, as long as n is at least 30.

For a proportion p in a sample of size n, the sampling distribution of the sample proportion will be approximately normal with mean $\mu = p$ and standard deviation $s = \sqrt{\frac{p(1-p)}{n}}$

Subtraction between normal variables:

When two normal variables are subtracted, the mean is the difference of the means, while the standard deviation is the square root of the sum of the variances.

1999:

20 out of 100 in the bottom third, so:

$p_1 = \frac{20}{100} = 0.2$

$s_1 = \sqrt{\frac{0.2*0.8}{100}} = 0.04$

2001:

10 out of 100 in the bottom third, so:

$p_2 = \frac{10}{100} = 0.1$

$s_2 = \sqrt{\frac{0.1*0.9}{100}} = 0.03$

Test if proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced.

At the null hypothesis, we test if the proportion is still the same, that is, the subtraction of the proportions in 1999 and 2001 is 0, so:

$H_0: p_1 - p_2 = 0$

At the alternative hypothesis, we test if the proportion has been reduced, that is, the subtraction of the proportion in 1999 by the proportion in 2001 is positive. So:

$H_1: p_1 - p_2 > 0$

The test statistic is:

$z = \frac{X - \mu}{s}$

In which X is the sample mean, $\mu$ is the value tested at the null hypothesis, and s is the standard error.

0 is tested at the null hypothesis:

This means that $\mu = 0$

From the two samples:

$X = p_1 - p_2 = 0.2 - 0.1 = 0.1$

$s = \sqrt{s_1^2 + s_2^2} = \sqrt{0.04^2 + 0.03^2} = 0.05$

Value of the test statistic:

$z = \frac{X - \mu}{s}$

$z = \frac{0.1 - 0}{0.05}$

$z = 2$

P-value of the test and decision:

The p-value of the test is the probability of finding a difference of at least 0.1, which is the p-value of z = 2.

Looking at the z-table, the p-value of z = 2 is 0.9772.

1 - 0.9772 = 0.0228.

The p-value of the test is 0.0228, which is less than the standard significance level of 0.05, which means that there is evidence that the proportion of freshmen who graduated in the bottom third of their high school class in 2001 has been reduced.

5 0

2 years ago

How do you do number 15 and 17? Help please?

vodomira [7]

15)

m = Miguel Indurian titles amount l = Lance Armstrong titles amount

they both won titles to the tour de france, if we add all together, they sum up to 12 for both of them
so.. whatever "m" and "l" are, we could say that m + l = 12

now... Miguel won 2 fewer than Lance, so, whatever "l" is, m = l - 2
thus $\bf \begin{cases}
\boxed{m}=l-2\\\\
m+l=12\\
----------\\
\left( \boxed{l-2} \right)+l=12
\end{cases}$

solve for "l", to see how many Lance won

how many did Miguel win? well, m = l - 2

---------------------------------------------------------------------------------

17)

c = mgs amount in 12oz cup of regular coffee at starbucks
d = mgs amount in 12oz cup of regular decaffeinated coffee at starbucks

we know the regular coffee cup, has 13 times more than the decaf, same 12ouncer

thus whatever "c" and "d" are, we know that c = 13d
both 12ouncers put together, yield 280mgs of caffeine

so, one could say that whatever "c" and "d" are, c + d = 280

thus $\bf \begin{cases}
\boxed{c}=13d\\\\
c+d=280\\
----------\\
\left( \boxed{13d}\right)+d=280
\end{cases}$

solve for "d" to see how much is in the decaffed cup

the regular coffee cup? well c = 13d

8 0

3 years ago

In the equation 9^2 x 27^3 = 3^x, what is the value of x? Show your work on scratchpaper

IceJOKER [234]

Answer:

x=13

Step-by-step explanation:

9^2 * 27^3 = 3^x

We need to get each term with a base of 3

9^2 = (3^2) ^2

We know that a^b^c = a^(b*c)

(3^2) ^2 = 3^(2+2) = 3^4

27^3 = (3^3) ^3 = 3^(3*3) = 3^9

Replacing these in the original equation

3^4 * 3^9 = 3^x

We know that a^b *a^c = a^(b+c)

3^4 * 3^9 =3^(4+9) = 3^13 = 3^x

The bases are the same, so the exponents must be the same

x=13

7 0

3 years ago