149.11 141. In how many ways 21 red...
Question

149.11 141. In how many ways 21 red balls and 19 blue balls can be arranged in a row so that no two blue balls are together? (a) 1,540 (b) 1,520 (C) 1,560 (d) None 5.19

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Maths
Solution
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first put 21 red balls 19 blue bash : bals in the gip ( rightarrow ) 21 sed bals can be praced in 1 way (auar identical) Gaps Aeatest = Oreated = 22 ( N^{prime} frac{20 j v^{2}}{r a t^{prime} cdots g}=frac{22 times 2 r^{7} times 20}{3 times 2} ) ( =22 times 70 ) ( =1540 ) - a antion