22. Correct. The answer is true.
4 senior mining companies out of 7 can be selected in 7C4
ways.
2 junior mining companies out of 6 can be selected in 6C2
ways.
The total number of possible selections is:
7C4 * 6C2
= [7!/(4!*3!)] * [6!/(2!*4!)]
= [(7*6*5*4*3*2*1)/(4*3*2*1*3*2*1)] *
[(6*5*4*3*2*1)/(2*1*4*3*2*1)]
= 35 * 15 = 525 different combinations