In a survey of buying habits, 400 women shoppers are chosen at random in super market ‘A’ located in a certain section of the city. Their average weekly food expenditure is \$250 with a standard deviation of \$40. For 400 women shoppers chosen at random in super market ‘B’ in another section of the city, the average weekly food expenditure is \$220 with a standard deviation of \$55. Test at 1% level of significance whether the average weekly food expenditure of the two populations of shoppers are equal. (At 1% level of significance, the critical value of Z = ±2.58).