Page 9 ADM 2303- Spring/Summer 2022 The indoor pool at the local YMCA uses a filtration system to keep the pool water clean. This system requires that the filter be backwashed when the discharge pressure for the water pump reaches 25 psi. the average time between backwashing is 10 days and this time period follows the exponential probability distribution. What is the standard deviation of the time between backwashing? a) 10 b) 0.1 c) 0.01 d) 100 e) 0.001 What is the probability that the next backwash will occur between 6 and 9 days from the prior backwash? a) 0.011 b) 0.420 c) 0.501 d) 0.122 e) 0.142 According to Pew Research, 50% of people over 30 and 75% of teenagers were using social networking site in early 2012. Most of that activity was on Facebook, so let's assume these probabilities apply strictly to Facebook. Among a group of 10 people, what's the probability that: At least one of the people was not on Facebook if half were teenagers? a) 0.739 b) 0.893 c) 0.993 d) 0.793 e) 0.593