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pentagon [3]
2 years ago
14

Melinda and Paula shovel driveways and sidewalks in the winter as a way to earn extra money. Together they shoveled 450 square f

eet of sidewalk in 30 minutes. Then Melinda shoveled for 20 minutes while Paula shoveled for 25 minutes to complete 345 square feet of driveway. 30x + 30y = 450 20x + 25y = 345 How much more can Paula shovel in 1 minute than Melinda?
Mathematics
2 answers:
dlinn [17]2 years ago
8 0

Answer:

Answer is A

Step-by-step explanation:

Took it on Edg.

IrinaK [193]2 years ago
4 0

Answer:

3 more square feet.

Step-by-step explanation:

x = The amount Melinda can shovel in 1 minute

y = The amount Paula can shovel in 1 minute

So make two equations:

30(x + y) = 450       x + y = 15       x = 15 - y

20x + 25y = 345     4x + 5y = 69

Plug in:

4(15 - y) + 5y = 69

60 - 4y + 5y = 69

y = 9

x = 6

9 - 6 = 3

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A study was performed on green sea turtles inhabiting a certain area.​ Time-depth recorders were deployed on 6 of the 76 capture
polet [3.4K]

Answer:

One can be 99% confident the true mean shell length lies within the above interval.

The population has a relative frequency distribution that is approximately normal.

Step-by-step explanation:

We are given that Time-depth recorders were deployed on 6 of the 76 captured turtles. These 6 turtles had a mean shell length of 51.3 cm and a standard deviation of 6.6 cm.  

The pivotal quantity for a 99% confidence interval for the true mean shell length is given by;

                    P.Q.  =  \frac{\bar X-\mu}{\frac{s}{\sqrt{n} } }  ~ t_n_-_1

where, \bar X = sample mean shell length = 51.3 cm

             s = sample standard deviation = 6.6 cm

             n = sample of turtles = 6

             \mu = true mean shell length

Now, the 99% confidence interval for \mu =  \bar X \pm t_(_\frac{\alpha}{2}_)  \times \frac{s}{\sqrt{n} }

Here, \alpha = 1% so  (\frac{\alpha}{2}) = 0.5%. So, the critical value of t at 0.5% significance level and 5 (6-1) degree of freedom is 4.032.

<u>So, 99% confidence interval for</u> \mu  =  51.3 \pm 4.032 \times \frac{6.6}{\sqrt{6} }

                                                         = [51.3 - 10.864 , 51.3 + 10.864]

                                                         = [40.44 cm, 62.16 cm]

The interpretation of the above result is that we are 99% confident that the true mean shell length lie within the above interval of [40.44 cm, 62.16 cm].

The assumption about the distribution of shell lengths must be true in order for the confidence interval, part a, to be valid is that;

C. The population has a relative frequency distribution that is approximately normal.

This assumption is reasonably satisfied as the data comes from the whole 76 turtles and also we don't know about population standard deviation.

3 0
2 years ago
mary is preparing for her college entrance exams. in a practice test, she answered 12 problems in 30 minutes. at this rate, how
mariarad [96]
12 problems = 30 minutes
24 problems = 60 minutes
36 problems= 90 minutes
48 problems = 120 minutes
60 problems = 150 minutes 

Mary can respond 60 problems in 2 hours and 30 minutes/ 2 hours and half/ 150 minutes.

Hope this helps xx
3 0
2 years ago
Read 2 more answers
Determine all natural numbers x,y and z such that x
icang [17]

Question incomplete

Answered by Gauthmath must click thanks and mark brainliest

8 0
1 year ago
The number of cities in a region over time is represented by the function C(x)=2.9(1.05)^x. The approximate number of people per
N76 [4]

Answer:

B. T(x) = 2.9\cdot (1.05)^{4\cdot x + 5}

Step-by-step explanation:

The approximate population in the region is the product of the number of cities in a region and the approximate number of people per city, that is:

T(x) = C(x)\cdot P(x) (1)

If we know that C(x) = 2.9\cdot (1.05)^{x} and P(x) = (1.05)^{3\cdot x + 5}, then the formula for the approximate population in the region is:

T(x) = [2.9\cdot (1.05)^{x}]\cdot [(1.05)^{3\cdot x + 5}]

T(x) = 2.9\cdot (1.05)^{4\cdot x + 5}

Hence, correct answer is B.

3 0
2 years ago
angela fully charged her laptop, then unplugged it and tracked the battery level at certain times under constant use. the table
DochEvi [55]

Answer:

%=-7t

solution -7% per 1:00

Step-by-step explanation:

Hope this helps

3 0
2 years ago
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