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Tamiku [17]
3 years ago
6

Ana can finish a certain job in 10 hours. Together, Ana and Nina can finish the same job in 3 hours. How many hours can Nina fin

ish the job alone?
Mathematics
1 answer:
Over [174]3 years ago
5 0

Answer:   4.5 hours

<u>Step-by-step explanation:</u>

Ana: \dfrac{1}{10}\ \text{job per hour}\\\\Nina: \dfrac{1}{x}\ \text{job per hour}\\\\Together: \dfrac{1}{3}\ \text{job per hour}\\\\\\Ana + Nina = Together\\\dfrac{1}{10}\quad +\dfrac{1}{x}\quad =\quad \dfrac{1}{3}\\\\\\\dfrac{1}{10}(30x)+\dfrac{1}{x}(30x) =\dfrac{1}{3}(30x)\\\\\\\rightarrow\quad 3x+30=10x\\\\.\quad 3x+30=10x\\\underline{-3x\qquad \quad -3x\quad}\\.\qquad \quad 30=7x\\\\.\qquad \quad \dfrac{30}{7}=\dfrac{7x}{7}\\\\\\.\qquad \quad \dfrac{30}{7}=x

.\qquad \quad 4.5=x

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One of the authors came across an article (USA Today, 2008) that said that on average Americans have visited 16 states in the Un
Daniel [21]

Answer:

1. a. Students

2. d. number of U.S. states visited, quantitative

3. a. H o: mu = 16, Ha: mu ≠ 16

4. (7.46,11.50)

Step-by-step explanation:

1. The researcher is interested in finding out the average number of states in US that the students have visited.

The unit that is being observed to arrive at that conclusion is the Students. The observational unit for this study is  a. Students.

2. The variable of interest from the information above is the number of U.S. states visited. The observations recorded for this variable are in numbers which are numeric in nature. This implies that the variable is quantitative in nature.

Therefore, the answe  is d. number of U.S. states visited, quantitative

3. To test whether the average number of states all students at the author’s school have visited,

The null hypothesis (H o) is always given as the negation statement/null of what we wish to test.

So, we wish to test that the average is different from 16. Therefore, the null would be that the average is 16.

Answer  is a. H o: mu = 16, Ha: mu ≠ 16

4. A  95% confidence interval for the average number of states all students at the author’s school have visited can be calculated using the formula:

x  bar + or - 2 √s/n

=9.48 + or - 2 × 7.13/ √50

= (7.46,11.50)

The 95% confidence interval for the average number of states all students at the author’s school have visited is (7.46,11.50). The average falls betw 7.64 and 11.50.

7 0
3 years ago
5. Two shelves are on a wall with one directly above the other. One shelf is 4 5/6 feet above the floor and the other is 5% 9/10
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5 9/10 - 4 5/6 = (5x10+9)/10 - (4x6+5)/6 = 59/10 - 29/6 = 177/30 - 145/30 = 32/30 = 1 1/15 feet apart
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3 years ago
Danielle plotted 3 points from the equation y = 4x on this coordinate grid. She drew a straight line through the points. Which o
Evgen [1.6K]
3... y= 4x means 3x4=12
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3 years ago
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I need help please fast .................
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Answer:

I have no idea what sohcahtoa is but:

tan 50.1° = x/5

1.196 = x/5

multiply both sides of the equation by 5:

x = 5.98

3 0
3 years ago
Can somebody help me ??
fiasKO [112]

Answer: C

Step-by-step explanation:

Formula: V=\pi r^2h

We do not have the radius, but we do have the diameter. A diameter is twice the radius, therefore we can divide the diameter by 2 in order to obtain the radius.

\frac{d}{2}=\frac{12}{2}  =6

Plug this info into the formula.

V=\pi r^2h\\V=\pi (6)^2(7)\\V=\pi 36*7\\V=252\pi in^3

4 0
3 years ago
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