Answer:
57%
Explanation:
Given
Number of kids = 25
Probability that 20 or fewer kids like Pizza = 43%
Required
Probability that at least 21 kids in the same group like pizza
In probability, summation of opposite probabilities is always equal to 1;
The opposite of 20 or fewer kids is 21 or more kids
21 or more kids means at least 21 kids
Since we mentioned that summation of opposite probability is always equal to 1
This can be represented as follows;
Probability of 20 or fewer kids + Probability of 21 or more kids = 1
Given that Probability that 20 or fewer kids like Pizza is 43%;
By substitution, we have
43% + Probability of 21 or more kids = 1
Collect like terms
Probability of 21 or more kids = 1 - 43%
Convert percentage to decimal
Probability of 21 or more kids = 1 - 0.43
Probability of 21 or more kids = 0.57
Convert decimal to percentage
Probability of 21 or more kids = 57%
Hence, the probability that at least 21 kids in the group like Pizza is 57%