• # question_answer The total number of combinations 6 at a time which can be formed from 6 alike white, 6 alike blue, 6 alike green & 6 alike red balls is: A) 90 B) 84 C) 78 D) none of these

[ 9 cases]  0 0 0 0 0 0 0 0 0$={}^{9}{{C}_{3}}=84$ or co-eff. of ${{x}^{6}}$in ${{(1+x+{{x}^{2}}+{{x}^{3}}+{{x}^{4}}+{{x}^{5}}+{{x}^{6}})}^{4}}$ Treat W, B, G, R as begger]