Find the number of 4-digit numbers that contain at least three odd digits.

3000

Step-by-step explanation:

First find the 4 digit numbers that have all odd digits

Possible Odd digits  =5(1,3,5,7,9)  

So, total number of 4 digit numbers with odd digits can be calculated as  =5×5×5×5=625

Now find all the 4 digits numbers with at least 3 odd digits and the first digit as either 2,4,6,8 ( 0 would make it a 3 digit number)

The first digit can be 2,4,6,8

=4×5×5×5=500

Now find all the 4 digits numbers with at least 3 odd digits and the second digit as either 0,2,4,6,8

=5×5×5×5=625

Now find all the 4 digits numbers with at least 3 odd digits and the third digit as either 0,2,4,6,8

Now find all the 4 digits numbers with at least 3 odd digits and the second digit as either 0,2,4,6,8

=5×5×5×5=625

Now find all the 4 digits numbers with at least 3 odd digits and the fourth digit as either 0,2,4,6,8

=5×5×5×5=625

Add them together

625+500+625+625+625=3000

arithmetic sequence

step-by-step explanation:

given that a sequence has terms as

19, 15, 11,

this is represented on a graph

the pattern indicates that the sequence is an arithmetic sequence with i term

a=19 and common difference d =-4

any general term

thus the sequence is reduced by 4 for each successive term starting from 1 and nth term is

24-5n.

first negative term would start after 5th term

5th term =24-25< 0

from 5th term onwards the sequence would be negative.