Answer: 0.271
Step-by-step explanation:
Probability of complement of an even is 1 decreased by the probability of the event
P(At least one) =1 - P(none)
The probability that of testing negative is 0.9 because the probability of testing positive is 0.1
P( at least one) = 1 - P(none) = 1 - (0.93^3) = 0.271