(a) Out of the 100 pregnant women, 98% of them will test positive, which is 98 women. Out of the 900 non-pregnant women, 1% of them will test positive, which is 9 women. Therefore, out of the total 1,000 women, 98 + 9 = 107 women will test positive. The probability that a randomly chosen woman from this group will test positive is 107/1000 = 0.107 or 10.7%.

(b) Out of the 50 pregnant women, 98% of them will test positive, which is 49 women. Out of the 950 non-pregnant women, 1% of them will test positive, which is 9.5 women (rounded to 10 for simplicity). Therefore, out of the total 1,000 women, 49 + 10 = 59 women will test positive. The probability that a randomly chosen woman from this group will test positive is 59/1000 = 0.059 or 5.9%.