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3 years ago

PLEASE HELP!!

Mathematics

1 answer:

lisabon 2012 [21]3 years ago

8 0

this is a. same area this is correct I think so

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A professor records the difference between the marks scored by the students in the class test last week and those scored in the

dezoksy [38]

Answer: $(10.82\ , 13.18)$

Step-by-step explanation:

The confidence interval for population mean is given by :-

$\mu\pm\ z_{\alpha/2}\dfrac{\sigma}{\sqrt{n}}$

Given : Sample size : n= 35 , large sample (n>30)

Mean difference : $\overline{x}=12$

Standard deviation : $\sigma=3$

Significance level : $\alpha=- 1-0.999=0.001$

Critical value : $z_{\alpha/2}=z_{0.0005}=3.4807567$

Now, the 99.9% confidence interval for the mean difference between the marks scored last week and marks scored this week by all the students will be :-

$12\pm\ (3.4807567)\dfrac{2}{\sqrt{35}}\\\\=12\pm1.18\\\\=(10.82\ , 13.18)$

Hence, the 99.9% confidence interval for the mean difference between the marks scored last week and marks scored this week by all the students = $(10.82\ , 13.18)$

4 0

3 years ago

In ΔXYZ, x = 8.3 meters, y = 9 meters, and z = 15 meters. Find the remaining measurements of the triangle, and round your answer

laila [671]

Answer:

<u>The correct answer is B. ∠X = 28.6°, ∠Y = 31.2°, ∠Z = 120.2°</u>

Step-by-step explanation:

Let's recall that for solving a SSS triangle, we :

1. Use the Law of Cosines first to calculate one of the angles

2. Use The Law of Cosines again to find another angle

3. Finally use angles of a triangle add to 180° to find the last angle.

1. Cos x = (9² + 15² - 8.3²/2 * 9 * 15)

Cos x = (81 + 225 - 68.89/270)

Cos x = 0.878

x = Cos ⁻¹ (0.878)

x = 28.6° (rounding to the next tenth)

2. Cos y = (8.3² + 15² - 9²/2 * 8.3 * 15)

Cos y = (68.89 + 225 - 81/249)

Cos y = 0.855

x = Cos ⁻¹ (0.855)

x = 31.2° (rounding to the next tenth)

3. z = 180 - 31.2 - 28.6

z = 120.2°

<u>The correct answer is B. ∠X = 28.6°, ∠Y = 31.2°, ∠Z = 120.2°</u>

4 0

3 years ago

The distance a spring will stretch varies directly with how much weight is attached to the spring. if a spring stretches 9 inche

Tcecarenko [31]

9/100 = x/90
Cross multiply to get 810 = 100x
Divide both sides by 100 to get x = 81 inches

6 0

3 years ago

Help please . What does ad equal

tangare [24]

Answer:

AD also equal 14

Step-by-step explanation:

7 0

3 years ago

Read 2 more answers

Dean's Diner offers its clients a choice of regular and diet soda. Last night, the diner served 50 sodas in all, 90% of which we

Montano1993 [528]

Answer:

The diner served 45 regular sodas

Step-by-step explanation:

90% of 50 is 45 so the answer is 45

8 0

3 years ago