Answer: 500
Step-by-step explanation:
we have 60,000 fans that will arrive in 30 min
one security staff needs 15 seconds to screen one person,
one security staff will screen 4 people in one minute
one security staff will be able to screen just 120 people in 30 minutes
(4*30=120)
we have 60,000 people
60,000/120=500