Answer: 0.2857
<u>Step-by-step explanation:</u>
At least one teacher means exactly 1 or exactly 2 or exactly 3 teachers. Find the probability of each and add them up.

One teacher + Two teachers + Three teachers = 0.2857
<span>(2*h)/15 = 20 // - 20
(2*h)/15-20 = 0
2/15*h-20 = 0 // + 20
2/15*h = 20 // : 2/15
h = 20/2/15
h = 150
h = 150</span>
s = 2(lw + lh + wh)
Divide each side by 2 : s/2 = lw + lh + wh
Subtract 'lh' from each side: s/2 - lh = lw + wh
Combine the 'w' terms: s/2 - lh = w(l + h)
Divide each side by (l + h): (s/2 - lh) / (l + h) = w
N/d = 2/3 -------------------> 3n = 2d
(n + 2)/(d + 2) = 3/4 ------> 4n + 8 = 3d + 6
So 20% of 30 is 6
30% * 30 is 9
Alexa completed 6 of 30 questions
Brent completed 9 of 30 questions
Brent completed 3 more questions than Alexa
Hope this helps :)