irb(main):001:0> no_of_customers = 3
#=> 3
irb(main):002:0> no_of_customers == 1 ? (customer_noun = "customer") : (customer_noun = "customers")
#=> "customers"
irb(main):003:0> puts "#{no_of_customers} #{customer_noun}."
#=> 3 customers.

# Did you know that in Ruby on Rails you can simply write this, instead?
puts "#{no_of_customers} #{"customer".pluralize(no_of_customers)}."