The average weight of P, Q and R is $47\text{kg}$. If the average weight of Q and R is $50\text{kg}$ and that of R and P is $49\text{kg}$, then the average weight (in $\text{kg}$) of P and Q is:

From the given information, we can establish the sums of weights:Total weight of P, Q, and R:
$$P+Q+R=3\times 47=141\text{kg}$$
Total weight of Q and R:
$$Q+R=2\times 50=100\text{kg}$$
Total weight of R and P:
$$R+P=2\times 49=98\text{kg}$$
Subtracting equation (2) from equation (1) provides the weight of P:
$$P=(P+Q+R)-(Q+R)=141-100=41\text{kg}$$
Substitute $P=41$ into equation (3) to find the weight of R:
$$41+R=98⟹R=98-41=57\text{kg}$$
Substitute $R=57$ into equation (2) to find the weight of Q:
$$Q+57=100⟹Q=100-57=43\text{kg}$$
Now, calculate the average weight of P and Q:
$$\text{Average weight of P and Q}=\frac{P+Q}{2}=\frac{41+43}{2}=\frac{84}{2}=42\text{kg}$$