1/9 = 1.11
29/8 = 3.63
-------
3.73 = 269/72
or....
1/9 >>> 8/72 (72 is the common denominator) (Multiply the N and D by 8)
29/8 >>> 261/72 (72 is the common denominator) (Multiply the N and D by 9)
-------------
269/72
Answer:
Step-by-step explanation:
Let x be the random variable representing the times a fire department takes to arrive at the scene of an emergency. Since the population mean and population standard deviation are known, we would apply the formula,
z = (x - µ)/σ
Where
x = sample mean
µ = population mean
σ = standard deviation
From the information given,
µ = 6 minutes
σ = 1 minute
the probability that fire department arrives at the scene in case of an emergency between 4 minutes and 8 minutes is expressed as
P(4 ≤ x ≤ 8)
For x = 4,
z = (4 - 6)/1 = - 2
Looking at the normal distribution table, the probability corresponding to the z score is 0.023
For x = 8
z = (8 - 6)/1 = 2
Looking at the normal distribution table, the probability corresponding to the z score is 0.98
Therefore,
P(4 ≤ x ≤ 8) = 0.98 - 0.23 = 0.75
The percent of emergencies that the fire department arrive at the scene in between 4 minutes and 8 minutes is
0.75 × 100 = 75%
We can determine the correct graph by finding its roots
x² - 4x - 12 = 0
x² - 6x + 2x - 12 = 0
x(x-6) +2(x-6) = 0
(x+2)(x-6) = 0
This means the roots of the function are x=-2, and x=6 and the graph will cross x axis at these two points. From the given graphs, the graph B seems to cross these points.
So the answer to this question is option B
