Answer: 5.37
Step-by-step explanation:
Let x = ACT scores.
Given: ACT scores have a mean of 20.8 and 9 percent of the scores are above 28. The scores have a distribution that is approximately normal.
i.e. P(X>28)=0.09 (i)
Now,
(ii)
One -tailed z value for p-value of 0.09 =1.3408 [By z-table]
From (i) and (ii)
Hence, the standard deviation = 5.37
Step-by-step explanation:
Let a be base side and h be the height.
Volume of box, V = a²h
The sides of the box will cost $3 per m² and the base will cost $4 per m². Cost for making is $48.
That is
4a² + 3 x 4 x a x h = 48
4a² + 12 a x h = 48
a² + 3 ah = 12
So volume is
At maximum volume we have derivative is zero,
Negative side is not possible, hence side of square base is 2m.
Substituting in a² + 3 ah = 12
2² + 3 x 2 x h = 12
h = 1.33 m
Dimension of box is 2 m x 2 m x 1.33 m