Question

6: Suppose the wait to pass through immigration at JFK Airport in New York is thought to be bell-shaped and symmetrical with a mean of 60 minutes. It is known that about 95% of travelers will spend between 30 and 90 minutes waiting to pass through immigration. The standard deviation for the wait time through immigration is A 10 minutes B. 15 minutes C. 20 minutes D. 30 minutes

Answer 1

let X : The wait to Soluhon pass through immigration at JFK airport in New York (in minutes) X' follows bell shapes and symmenicah dishbution with mean = 60 minutes > 95% data (shaded region) - 00 co 30 mean - 60 minute 90 we have given that 30 and go minutes waiting About 95% of travelers will spend between pass through immigration. the probability to That is =0.95 P130 < x s90] - 95 % → P [60-30 < X < 60+30] = 0.95 M=60= mean > P[W-30 ? x?fl +30] -0.95 2 Now, for 0.68 bell shaped and symmenica micas distibution, Cimpirical formula P[ll-o < x 0+0] = 68.6. - P[ 4-20 < x < M +20] = 95% = 0.95 P[4-30 < x < 4+ 30] - 99.7%. = 0.997 and U mean 5: standard devianon Now, compare eq? @ f © > P[4-30 < x < 4+30) - P[4-20 4X4 4+20] 20:30 o 15 minute s Hence, 'The Standard deviation for the wait time through immigration is 15 minutes