Question 392603
there are 4 even and 3 odd numbers....


a)
 no. of ways to form 4 digit numbers without repetition = 7P4 = 840



b) no. of ways to form 4 digit numbers with repetition = 7*7*7*7 = 7^4 = 2401



c) we can put odd digit on unit place be 3 ways and can arrange remaining 6 

digit on first 3 places by 6P3 ways, 

no. of odd numbers ( refer to a )  = 6P3 *  3 = 360




d) for unit place we can put digit by 4 ways and for other 3 places any digit

 no. of even numbers when repetition is allowed = 7*7*7*4 =1372