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2 years ago

ASAP please...........

Mathematics

2 answers:

Sunny_sXe [5.5K]2 years ago

5 0

Answer:

The answer is A

Step-by-step explanation:

It A because each book that he is buying cost 2.5 and the amount of books he buying is unknown so the variable x is place right next to 2.5. But if he wants to buy lunch he has to subtract 8 dollars from his total amount. So since David has a limit of $50 the symbol for the equation should be the less than symbol< because he has to be able to buy lunch and buy the book with less than 50 dollars.

The final equation should be 2.5x - 8< 50

Veseljchak [2.6K]2 years ago

4 0

Answer:

I think it would be b

Step-by-step explanation:

He doesn't want to spend more than 50 and he needs 8 for lunch so the 8 dollars and the book can't go over 50.

Its either a or b im just not sure if its plus 8 or minus 8. sorry

You might be interested in

(a/5) - (b/3) = (a/2) - (b/6), solve for a

Gnom [1K]

Answer:

$a = - \frac{10}{17} b$

Step-by-step explanation:

(a/5) - (b/3) = (a/2) - (b/6)

+(B/3) + (b/3)

NOTE: use property of equality to isolate b from a

(a/5) = (b/3) + (a/2) - (b/6)

-(a/2) - (a/2)

NOTE: continue to use property of equality to isolate a from b

(a/5) - (a/2) = (b/3) - (b/6)

60((a/5) - (a/2)) = ((b/3) - (b/6))60

NOTE: 60 is a common multiple of 5, 2, 3, and 6

12a - 30a = 20b - 10b

NOTE: combine alike terms

-17a = 10b

-17a/-17 = 10b/-17

NOTE: decide by -16 to find what a is equal to

$a = - \frac{10}{17} b$

Final answer

5 0

3 years ago

At a large Midwestern university, a simple random sample of 100 entering freshmen in 1993 found that 20 of the sampled freshmen

guajiro [1.7K]

Answer:

The 90% confidence interval for the difference of proportions is (0.01775,0.18225).

Step-by-step explanation:

Before building the confidence interval, 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.

p1 -> 1993

20 out of 100, so:

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

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

p2 -> 1997

10 out of 100, so:

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

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

Distribution of p1 – p2:

$p = p_1 - p_2 = 0.2 - 0.1 = 0.1$

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

Confidence interval:

$p \pm zs$

In which

z is the z-score that has a p-value of $1 - \frac{\alpha}{2}$ .

90% confidence level

So $\alpha = 0.1$ , z is the value of Z that has a p-value of $1 - \frac{0.1}{2} = 0.95$ , so $Z = 1.645$ .

The lower bound of the interval is:

$p - zs = 0.1 - 1.645*0.05 = 0.01775
$

The upper bound of the interval is:

$p + zs = 0.1 + 1.645*0.05 = 0.18225
$

The 90% confidence interval for the difference of proportions is (0.01775,0.18225).

6 0

3 years ago

For 15 points please help

iragen [17]

Answer:

The movers will need 3 crib-jacks

Step-by-step explanation:

Since each crib jack can lift 30,000lbs, and without the belongings it only weighs 90,000, which divided by 30,000 equals 3.

5 0

2 years ago

The expression below represents the number of bacteria in a petri dish after t hours. Interpret the meaning of the expression.

konstantin123 [22]

The answer is B) The initial number of bacteria is 57, and the growth rate is 31% per hour.

The expression shown is an exponential expression. An exponential expression usually takes the form $ab^{x}$ , as this one does. A represents the initial value, in this case-the initial number of bacteria. B represents the growth rate. When it is an increasing growth rate, it will begin with 1, because it will have everything it had before, plus the percent increase, the decimal portion. In this case, a=57, and b=0.31.