The average monthly salary of 19 members of a group is Rs. 16000. If one more members whose monthly salary is Rs. 20000 has joined the group, then the average salary of the group is
PQ and RS are common tangents to two circles intersecting at A and B. AB, when produced both sides, meet the tangents PQ and RS at X and Y, respectively. If AB = 3 cm, XY = 5 cm, then PQ (in cm) will be