sampling _ significance of proportions

1. One type of aircraft is found to develop engine trouble in 5 flights out of a total of 100 and another type in 7 flights out of a totai of 200 flights. Is there a significant difference in the two types of aircrafts so far as engine defects are concerned?
2.In a large city A, 20 per cent of a random sample of 900 school boys had a slight physical defect. In another large city B, 18.5 percent of a random sample of 1600 school boys had the same defect. Is the difference between the proportions significant?