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 39 minutes. It is known that 68% of travellers will spend between 23 and 55 minutes waiting to pass through immigration. The standard deviation for the wait time through immigration is __________blank. Question 6Answer a. 20 minutes b. 19 minutes c. 16 minutes d. 18 minutes