Question

What is the total number of ways of selecting at least one ring from 2 sets of 10 identical rings picking at least one from each set?

• A. $2^{20}-1$
• B. $(2^{10}-1{)}^2$
• C. $2^{20}$
• D. $2^{20}-2$

Answer 1

Answer: (B)

$(2^{10}-1{)}^2$

If we have to pick atleast 1 ring from each set, then it will be $2^{10}-1$ for each set. Hence, the total number of ways = $(2^{10}-1{)}^2$