So first, we find the probability that the highly demented dice will land on a 3. You will get 0.12.
If you roll the dice once, the probability of landing on a 3 or 4 is 0.12 + 0.21 = 0.33.
0.33 = 33/100.
33/100 * 300 == 99
If you want to estimate, then you round 0.33 to 1/3, and 1/3 * 300 is easily 100.
Let's create a proportion:
actual height: shadow length
using what we have, we make the ratio
7ft: 2ft, and the ft cancels out to 7: 2
next up, we set up a variable x. the ratio of the utility pole is
x ft: 11ft, and the ft cancels out to x: 11, like before.
7:2 = 7/2
x:11 = x/11
they are equal, so
7/2 = x/11
multiply both sides by 2:
7 = 2x/11
multiply both sides by 11:
77 = 2x
77/2 = x, and 77/2 is the answer