Question 1 (1 point)

What is the expression equivalent to xy ^ 2/9

DochEvi [55]

Answer:

hi someone help me too

Step-by-step explanation:

6 0

3 years ago

I need some help with this question. It says: expand and simplify 5(x + 7) + 3(x - 2)

Tanya [424]

Answer:

8x+29

Step-by-step explanation:

open the brackets the collect like terms together

5 0

2 years ago

Let the following sample of 8 observations be drawn from a normal population with unknown mean and standard deviation:

Vikentia [17]

Answer:

a

$\= x = 18.5$ , $\sigma = 5.15$

b

$15.505 < \mu < 21.495$

c

$14.93 < \mu < 22.069$

Step-by-step explanation:

From the question we are are told that

The sample data is 21, 14, 13, 24, 17, 22, 25, 12

The sample size is n = 8

Generally the ample mean is evaluated as

$\= x = \frac{\sum x }{n}$

$\= x = \frac{ 21 + 14 + 13 + 24 + 17 + 22+ 25 + 12 }{8}$

$\= x = 18.5$

Generally the standard deviation is mathematically evaluated as

$\sigma = \sqrt{\frac{\sum (x- \=x )^2}{n}}$

$\sigma = \sqrt{\frac{\sum ((21 - 18.5)^2 + (14-18.5)^2+ (13-18.5)^2+ (24-18.5)^2+ (17-18.5)^2+ (22-18.5)^2+ (25-18.5)^2+ (12 -18.5)^2 )}{8}}$

$\sigma = 5.15$

considering part b

Given that the confidence level is 90% then the significance level is evaluated as

$\alpha = 100-90$

$\alpha = 10\%$

$\alpha = 0.10$

Next we obtain the critical value of $\frac{ \alpha }{2}$ from the normal distribution table the value is

$Z_{\frac{ \alpha }{2} } = 1.645$

The margin of error is mathematically represented as

$E = Z_{\frac{ \alpha }{2} } * \frac{\sigma }{\sqrt{n} }$

=> $E =1.645 * \frac{5.15 }{\sqrt{8} }$

=> $E = 2.995$

The 90% confidence interval is evaluated as

$\= x - E < \mu < \= x + E$

substituting values

$18.5 - 2.995 < \mu < 18.5 + 2.995$

$15.505 < \mu < 21.495$

considering part c

Given that the confidence level is 95% then the significance level is evaluated as

$\alpha = 100-95$

$\alpha = 5\%$

$\alpha = 0.05$

Next we obtain the critical value of $\frac{ \alpha }{2}$ from the normal distribution table the value is

$Z_{\frac{ \alpha }{2} } = 1.96$

The margin of error is mathematically represented as

$E = Z_{\frac{ \alpha }{2} } * \frac{\sigma }{\sqrt{n} }$

=> $E =1.96 * \frac{5.15 }{\sqrt{8} }$

=> $E = 3.569$

The 95% confidence interval is evaluated as

$\= x - E < \mu < \= x + E$

substituting values

$18.5 - 3.569 < \mu < 18.5 + 3.569$

$14.93 < \mu < 22.069$

8 0

2 years ago

The weights of a certain dog breed are approximately normally distributed with a mean of μ = 55 pounds, and a standard deviation

weqwewe [10]

Answer:

(a)z=-1

(b)48.5 pounds

(c)61.5 pounds

Step-by-step explanation:

$z-score=\dfrac{x-\mu}{\sigma}$

Given:

Mean, μ = 55 pounds

Standard deviation,σ = 6 pounds.

(a)For a dog that weighs 49 pounds.

x=49 pounds

The z-score

$=\dfrac{49-55}{6}\\=\dfrac{-6}{6}\\\\=-1$

(b)When a dog has a z-score of -1.09

$-1.09=\dfrac{x-55}{6}\\x-55=-6.54\\x=55-6.54\\x=48.46 \approx 48.5$ pounds (to the nearest tenth)$

The weight of a dog with a z-score of -1.09 is 48.5 pounds.

(c)When a dog has a z-score of 1.09

$1.09=\dfrac{x-55}{6}\\x-55=6.54\\x=55+6.54\\x=61.54 \approx 61.5$ pounds (to the nearest tenth)$

The weight of a dog with a z-score of 1.09 is 61.5 pounds.

3 0

2 years ago

What is the radius of the circle defined by x2 + 2x + y2 + 6y − 39 = 0?<br> 49<br> 9<br> 7<br> 81

Bond [772]

radius = 7

the equation of a circle in standard form is

(x-a)² + (y-b)² = r²

where (a, b) are the coordinates of the centre and r is the radius

To obtain this form ' complete the square ' on both the x and y terms

x² + 2(1)x + 1 + y² + 2(3)y + 9 = 39 + 1 + 9

(x+1)² + (y+3)² = 49 ← in standard form

with centre (1, 3) and r = √49 = 7

7 0

3 years ago

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