Permutations and Combinations
No. of permutations of 25 dissimilar things taken more than 15 at a time when repetitions are allowed is
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How many words, with or without meaning, can be formed using all the letters of the word EQUATION, using each letter exactly once?
How many 4-digit numbers are there with no digit repeated?
be a set of n(≥3)
distance elements. The number of triplets (x,y,z)
of the A
elements in which at least two coordinates is equal to
a. nP3 b. n3−nP3 c. 3n2−2n
A is a set containing n elements. A subset P1 is chosen and A is reconstructed by replacing the elements of P1. The same process is repeated for subsets P1,P2,….,Pm with m>1. The number of ways of choosing P1,P2,….,Pm so that P1∪P2∪….∪Pm=A is (a)(2m−1)mn (b)(2n−1)m (c)(m+n)Cm (d) none of these
Rajdhani Express going from Bombay to Delhi stops at five intermediate stations, 10 passengers enter the train during the journey with 10 different ticket of two class. The number of different sets of tickets they may have is
d. none of these
How many 5 digit telephone numbers can be constructed using the digits 0 to 9 if each number starts with 67 and no digit appears more than once?
A train time table must be compiled for various days of the week, so that two trains twice a day depart for three days, one train daily for two days, and three trains once a day for two days. How many diferent time table can be compiled?
A forecast is to be made of the results of five cricket matches, each of which can be a win or a draw or a loss for Indian team. Let
number of forecasts with exactly 1 error
number of forecasts with exactly 3 error
number of forecasts with all five error
Then the correct statement(s) is/are
a. 2q=5r b. 8p−q
c. 8p−r d. 2(p+r)>q