You have to do a histogram here:
<span>11 sec: 2 people: probability is 2/50 = 1/25 = 0.04
12 sec: 5 people: probability is 5/50 = 1/10 = 0.1
13 sec: 8 people: probability is 8/50 = 4/25 = 0.16
</span>14 sec: 10 people: probability is 10/50 = 1/5 = 0.2
15 sec: 21 people: probability is 21/50 = 2.38
16 sec: 2 people: probability is 2/50 = 1/25 = 0.04
17 sec: 2 people: probability is 2/50 = 1/25 = 0.04
Yes, your work is correct.
The diagram does illustrate x²+6x+9=72. This is also represented by
(x+3)² = 72
We can take the square root of both sides:

When we evaluate this, the answers are x = -11.5 or x = 5.5.
This is how I would do it:
-8x=28-4y divide the entire equation by 4
-2x=7-y Put y back on the left and put x on the right
y=7-2x.
The polynomial is not factorable with rational numbers
25%
Divide 12 by 3 and you'll get 4.
That means 1/4 or a quarter of the 12 is 3.
(Convert the fraction to its percentage form)
1/4 or 1 divided by 4 equals 0.25
Multiply 0.25 by 100 and you'll get 25%