Answer:
$100
Step-by-step explanation:
8x= 160
160/8 = 20
x=20
5x = 100
Answer:
cost of 1 kg of washing powder is $1.2
Step-by-step explanation:
9 kg = $10.80
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cost for 1 kg =
Answer:


![Interval = [666.78, 781.62]](https://tex.z-dn.net/?f=Interval%20%3D%20%5B666.78%2C%20781.62%5D)
Step-by-step explanation:
Given
The data for 25 undergraduates
Solving (a): Range and Standard deviation
The range is:

From the dataset:


So:



The standard deviation is:

First, calculate the mean



So, the standard deviation is:




Solving (b): The interval of the 95% of the observation.
Using the emperical rule, we have:
![Interval = [\bar x - 2*\sigma, \bar x+ 2*\sigma]](https://tex.z-dn.net/?f=Interval%20%3D%20%5B%5Cbar%20x%20-%202%2A%5Csigma%2C%20%5Cbar%20x%2B%202%2A%5Csigma%5D)
![Interval = [724.2 - 2*28.71, 724.2 + 2*28.71]](https://tex.z-dn.net/?f=Interval%20%3D%20%5B724.2%20-%202%2A28.71%2C%20724.2%20%2B%202%2A28.71%5D)
![Interval = [666.78, 781.62]](https://tex.z-dn.net/?f=Interval%20%3D%20%5B666.78%2C%20781.62%5D)