Students at a liberal arts college study for an average of 10 hours per week with a standard deviation of 2 hours per week. The distribution of their study time happens to be uni-modal, symmetric and bell shaped. Approximately 68% of students study between 8 and B hours a week. What is the value of B

it lies between 8 hours and 12 hours in a week  

Step-by-step explanation:

Since in the question it is mentioned that the distribution consist of uni-modal, symmetric and bell shaped so here the empirical formual to be used for the mean and the standard deviation

Also the 68% would be fall within one standard deviation above and below the mean

Now

1 standard deviation below the mean is

= 10 - 2

= 8 hours

And, above the mean is

= 10 + 2

= 12 hours

Hence, it lies between 8 hours and 12 hours in a week  

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

exa:

)

3+11

14

step-by-step explanation:

from this example, we can see that subtracting with integers is the same as adding the opposite. we can solve using a number line or by using the saying "keep, change, change" to us solve. it is important to remember that we can subtract a negative and end up with a larger number than we started with.