Answer:
The probability that at least 280 of these students are smokers is 0.9664.
Step-by-step explanation:
Let the random variable <em>X</em> be defined as the number of students at a particular college who are smokers
The random variable <em>X</em> follows a Binomial distribution with parameters n = 500 and p = 0.60.
But the sample selected is too large and the probability of success is close to 0.50.
So a Normal approximation to binomial can be applied to approximate the distribution of X if the following conditions are satisfied:
1. np ≥ 10
2. n(1 - p) ≥ 10
Check the conditions as follows:

Thus, a Normal approximation to binomial can be applied.
So,

Compute the probability that at least 280 of these students are smokers as follows:
Apply continuity correction:
P (X ≥ 280) = P (X > 280 + 0.50)
= P (X > 280.50)

*Use a <em>z</em>-table for the probability.
Thus, the probability that at least 280 of these students are smokers is 0.9664.
Step-by-step explanation:
x/3-2/5=2x/15-3x
5x-6=2x-9
5x-2x=-9+6
3x=-3
3x/3=-3/3
x=-1
Answer:
A=13825
Step-by-step explanation:
Answer:
25. 
26. 
Step-by-step explanation:
For 25:
(area of a trapezoid)
(substitute terms)
(collect like terms)
(reduce the fraction by crossing out 2)
(calculate)
For 26:
(equation of area of a circle)
(enter the radius)
(communtative property to reorder the terms)