Answer:
The approximate probability that at least 2 children have been diagnosed with ASD among the 200 selected children is
0.01 or 1%.
Explanation:
Number of selected children = 200
The probability of no child been diagnosed with ASD = P(None) = 198/200 = 0.99
Therefore, the probability of at least two children been diagnosed with ASD = 1 - 0.99 = 0.01.
This is the same as:
If 2 children have been diagnosed with ASD,
therefore, the approximate probability that at least 2 children have been diagnosed is:
2/200 = 0.01. This value is equal to 1%.
The above are summed up in:
The probability of at least one = 1/200 = 0.05
Therefore, the probability of at least two = 0.05 * 2 = 0.01
b) Generally, to find the probability of at least one event happening, we calculate the probability of none and then subtract that result from 1. That is, P(at least one) = 1 – P(none). For two events happening, the sum of the probability of at least one in two places is deducted from 1 to get the probability of at least two.