A sales consultant for Herron Pharmaceuticals wished to confirm that their packet of 24 paracetamol tablets was cheaper at the retail level than their rival product. The sales consultant collected price data from two independent samples, of size 22 for Herron and 28 for the rival company. These yielded an average and variance for the retail price of Herron's product of 390 cents and 56 cents squared respectively, and 389 cents and 46 cents squared for the rival.

 Under the usual assumptions, determine a 90% confidence interval for the price difference (use Herron minus rival) stating only the upper limit of the interval in cents (round to the nearest whole number).