Answer:
4.72 hours/day
Step-by-step explanation:
Mean time spent watching TV (μ) = 2.8 hours a day
Standard deviation (σ) = 1.5 hours a day
The 90th percentile (upper 10%) of a normal distribution has an equivalent z-score of roughly z = 1.282. The minimum time spent watching TV, X, at the 90th percentile is:
On a typical day, you must watch at least 4.72 hours of TV to be in the upper 10%.
Answer:
Step-by-step explanation:
We know that the length is four times the width, so:
We also know the area, which is 324 m². The formula for area:
Insert the known values:
Solve for w. Simplify by removing parentheses:
Divide 4 from both sides to isolate the variable:
Find the square root of both sides:
The width is 9 m.
We know the width. Now find the length by using the area formula and inserting known values:
Solve for l. Divide both sides by 9:
The length of the rectangle is 36. (You can check: 4 times 9 is 36)
Now find the perimeter:
Insert values:
The perimeter is 90 m.
