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3 years ago

Assume that y varies inversely with x. If y=-6 when x=-2, find y when x=5?

1 answer:

7 0

Direct = divide proportions

Inverse = multiply proportions

This is inverse

6x2 = 5 x X

12= 5x

12/5 = 5x/5

2.4 = x

x = 2.4

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1. In school lottery to win a price for "Free Domino's Pizza" it is required to select 5 numbers (in any order) out of 40 number

barxatty [35]

Answer:

1/8 ;

12 / 51

Step-by-step explanation:

To select any 5 numbers out of 40

Number of selection required / total numbers

Probability of winning = 5 /40 = 1/8

Total number of socks = 18

White, W = 8

Black, B = 6

Blue, C = 4

probability, without looking in the drawer, that you will first select and remove a black pair, then select either a blue or a white pair?

P(B) * [(P(C) + P(W)]

Probability = required outcome / Total possible outcomes

P(B) = 6 / 18 = 1/3

Without replacement :

P(W or C) = 8/17 + 4/17 = 12/17

Hence,

1/3 * 12/17

= 12 / 51

8 0

3 years ago

PLEASE MATH HELP WILL GIVE BRAINLIEST!!

saw5 [17]

Hello,

Answer B

(x-(-5))²+(y-2)²=5²

(x+5)²+(y-2)²=25

5 0

3 years ago

siniylev [52]

Answer:

Slant height (s)= 12.1 cm

Step-by-step explanation:

Given: Base= 4.5 cm.

Surface area of right square pyramid= 129.5 cm.

First, calculating slant height (s) of right square pyramid.

Surface area of square pyramid= $(a^{2} +2\times a\times s)$

a= side of square base.

s= slant height

∴ $129.5= (4.5^{2} + 2\times 4.5\times s)$

⇒ $129.5= (20.25+2\times 4.5\times s)$

⇒ $129.5= (20.25+9\times s)$

Now, opening the parenthesis and subtracting both side by 20.25.

⇒ $109.25=9\times s$

cross multiplying both side

∴ Slant height (s)= 12.1

5 0

3 years ago

Please answer this correctly

Troyanec [42]

Answer:

Mode

Step-by-step explanation:

Mean:

Before replacing = 464/8 = 58

After replacing 42 with 98 = 520/8 = 65

Mode:

Before replacing = 42

After replacing 42 with 98 = 98

Median:

25, 42 , 42 , 47, 55 , 59, 96,98

Before replacing = 47+55/2 = 51

25, 42 , 47, 55 , 59, 96,98 , 98

After replacing 42 with 98 = 55+59/2 = 114/2 = 57

8 0

2 years ago

An SRS of 350 high school seniors gained an average of x¯=21 points in their second attempt at the SAT Mathematics exam. Assume

Lynna [10]

Answer:

a) $21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

b) $ME=2.58\frac{52}{\sqrt{350}}=7.17$

c) $ME=2.58\frac{52}{\sqrt{100}}=13.42$

d) D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

Step-by-step explanation:

Previous concepts

A confidence interval is "a range of values that’s likely to include a population value with a certain degree of confidence. It is often expressed a % whereby a population means lies between an upper and lower interval".

The margin of error is the range of values below and above the sample statistic in a confidence interval.

Normal distribution, is a "probability distribution that is symmetric about the mean, showing that data near the mean are more frequent in occurrence than data far from the mean".

Part a

$\bar X=21$ represent the sample mean

$\mu$ population mean (variable of interest)

$\sigma=52$ represent the population standard deviation

n=350 represent the sample size

99% confidence interval

The confidence interval for the mean is given by the following formula:

$\bar X \pm z_{\alpha/2}\frac{\sigma}{\sqrt{n}}$ (1)

Since the Confidence is 0.99 or 99%, the value of $\alpha=0.01$ and $\alpha/2 =0.005$ , and we can use excel, a calculator or a table to find the critical value. The excel command would be: "=-NORM.INV(0.005,0,1)".And we see that $z_{\alpha/2}=2.58$

Now we have everything in order to replace into formula (1):

$21-2.58\frac{52}{\sqrt{350}}=13.83$

$21+2.58\frac{52}{\sqrt{350}}=28.17$

So on this case the 99% confidence interval would be given by (13.83;28.17)

Part b

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{350}}=7.17$

Part c

The margin of error is given by:

$ME=2.58\frac{52}{\sqrt{100}}=13.42$

Part d

As we can see when we reduce the sample size we increase the margin of error so the best option for this case is:

D. Decreasing the sample size increases the margin of error, provided the confidence level and population standard deviation remain the same.

6 0

2 years ago