Cashier records from the last year show that 35% of all Ralph's grocery store customers use a previously-obtained Ralph's discount card upon checkout. Management suspects the percentage of actual cardholders is higher because some customers may not use their Ralph's card during every visit. They decide to sample random customers who enter the store, and ask them if they have a Ralph's card. Suppose they solicit 400 customers one day, and find that 160 of them have a Ralph's card.