The owner of a store wants to examine whether method of payment (with either cash, credit card, debit card or voucher) and age group (of either 18 years, between 18 to 40 years, and 40 years) of paying customers, are independent. The following table summarises the observed frequencies:

	Method of payment
Age	Cash	Credit card	Debit card	Voucher
18 years	5	10	22	20
between 18 to 40 years	22	3	20	23
40 years	22	21	14	12

What is the critical value if testing at of 5%?

Please give your answer correctly rounded to two decimal places.