Class 11

Math

JEE Main Questions

Permutations and Combinations

If $6!1 +7!1 =8!x ,$find x

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Find the number of ways in which $5A_{prime}sand6B_{′}s$ can be arranged in a row which reads the same backwards and forwards.

Let $f(n)$ be the number of regions in which $n$ coplanar circles can divide the plane. If it is known that each pair of circles intersect in two different points and no three of them have common points of intersection, then $(i)$ $f(20)=382$ $(ii)$ $f(n)$ is always an even number $(iii)$ $f_{−1}(92)=10$ $(iv)$ $f(n)$ can be odd

A box contains 2 white balls, 3 black balls & 4 red balls. In how many ways can three balls be drawn from the box if atleast one black ball is to be included in draw (the balls of the same colour are different)

How many five-digit numbers can be made having exactly two identical digits?

How many 3-digit numbers can be formed by using the digits 1 to 9 if no digit is repeated?

The total number of divisor of 480 that are of the form $4n+2,n≥0,$ is equal to a. $2$ b. $3$ c. $4$ d. none of these

How many 3-digit numbers can be formed from the digits 1, 2, 3, 4 and 5 assuming that(i) repetition of the digits is allowed?(ii) repetition of the digits is not allowed?

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?