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The number of six digit numbers that can be formed from the digits 1, 2, 3, 4, 5, 6 and 7 so that digits do not repeat and the terminal digits are even is (a) 144 (b) 72 (c) 288 (d) 720 (e) None of these |
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Answer» (d) The first and the last (terminal) digits are even and there are three even digits. This arrangement can be done in 3P2 ways. For any one of these arrangements, two even digits are used; and the remaining digits are 5(4 odd and 1 even) and the four digits in the six digits (leaving out the terminal digits) may be arranged using these 5 digits in 5P4 ways. The required number of numbers is 3P2 × 5P4 = 6 × 120 = 720. |
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