According to the Australian Red Cross Blood Service, 49% of people in Australia have O group blood, 38% have A group blood, 10% have B group blood, and 3% have AB group blood. A random sample of people produces the frequencies in the table below:

Blood type	Frequency
O	450
A	420
B	90
AB	40

a) Do you doubt the proportions claimed by the Australian Red Cross Blood Service? Perform a suitable test at the 5% significance level.