Answer:
30 hours
Step-by-step explanation:
The equation we use is 1/15 + 1/x = 1/10. X being the amount of time it takes Ian alone. X works out to 30 hours which is the answer
Answer is 60 U need to calculate carefully with brackets involving multiplication
Answer:
The standard deviation for the income of super shoppers is 76.12.
Step-by-step explanation:
The formula to compute the standard deviation for the grouped data probability distribution is:
![\sigma=\sqrt{\sum [(x-\mu)^{2}\cdot P(x)]}](https://tex.z-dn.net/?f=%5Csigma%3D%5Csqrt%7B%5Csum%20%5B%28x-%5Cmu%29%5E%7B2%7D%5Ccdot%20P%28x%29%5D%7D)
Here,
<em>x</em> = midpoints

Consider the Excel table attached below.
The mean is:

Compute the standard deviation as follows:
![\sigma=\sqrt{\sum [(x-\mu)^{2}\cdot P(x)]}](https://tex.z-dn.net/?f=%5Csigma%3D%5Csqrt%7B%5Csum%20%5B%28x-%5Cmu%29%5E%7B2%7D%5Ccdot%20P%28x%29%5D%7D)

Thus, the standard deviation for the income of super shoppers is 76.12.