Answer:
See explanation below
<u>Step-by-step explanation:</u>
range = 2200 - 300 = 1900
To find standard deviation, we have:
standard deviation = range/4 = 
= 475
The range rule of thumb estimate for the standard deviation is 475
Given:
Standard deviation,
= 475
Margin of Error, ME = 100
= 1 - 0.90 = 0.10
Za/2 = Z0.05 = 1.64
Find sample size, n:
n ≥ ![[Z_\alpha_/_2 * (\frac{\sigma}{ME})]^2](https://tex.z-dn.net/?f=%20%5BZ_%5Calpha_%2F_2%20%2A%20%28%5Cfrac%7B%5Csigma%7D%7BME%7D%29%5D%5E2%20)
n ≥ ![[1.64 * (\frac{475}{100})]^2](https://tex.z-dn.net/?f=%5B1.64%20%2A%20%28%5Cfrac%7B475%7D%7B100%7D%29%5D%5E2)
n ≥ 60.68
≈ 61
Minimun sample size,n = 61
Answer: the speed of the boat on the lake is 9 mph
Step-by-step explanation:
Let x represent the speed of the boat on the lake or in still water.
The speed of the current in a river is 6 mph. This means that if the boat goes upstream against the speed of the current, its total speed would be (x - 6)mph. If the boat goes downstream against the speed of the current, its total speed would be (x + 6)mph.
Time = distance/ speed
Every day, his route takes him 22.5 miles each way against the current and back to his dock, and he needs to make this trip in a total of 9 hours. This means that the time taken to travel upstream is
22.5/(x - 6). The time taken to travel downstream is
22.5/(x + 6)
Since the total time is 9 hours, it means that
22.5/(x - 6) = 22.5/(x + 6)
Cross multiplying, it becomes
22.5(x + 6) + 22.5(x - 6) = 9
Multiplying through by (x + 6)(x - 6), it becomes
22.5(x - 6) + 22.5(x + 6) = 9[(x + 6)(x - 6)]
22.5x - 135 + 22.5x + 135 = 9(x² - 6x + 6x - 36)
22.5x + 22.5x = 9x² - 324
9x² - 45x - 324 = 0
Dividing through by 9, it becomes
x² - 5x - 36 = 0
x² + 4x - 9x - 36 = 0
x(x + 4) - 9(x + 4) = 0
x - 9 = 0 or x + 4 = 0
x = 9 or x = - 4
Since the speed cannot be negative, then x = 9
Answer:
The answer is c: y = 35x + 1000
Step-by-step explanation:
Jamie starts off with 1000 which means that no matter how much more money she adds to the account she still has to add the 100 she already has. Then she is adding $35 per month so it would be positive 35 so the correct equation is
35x +1000
Answer:
Step-by-step explanation:
7 x > 4 x + 100
7 x - 4 x > 100
3 x > 100
x > 100 : 3
x > 33.33
<u><em>Answer: they have to sell 34 pizzas to make a profit.
</em></u>
Answer:
- Equation 3y = -42
- Solved: y = -14
Step-by-step explanation (to solve the equation):
- Divide each side by 3 to cancel out the 3 next to y. It should now look like this: y = -14
I hope this helps!
