Problems of the 2nd tour

Theme : Combinatorics (difficulty level : easy)

Name Age Country Problem
Problem 1 N.P 17 France An unknown coded alphabet contains 6 vowels and 8 consonants. To form a word, we have to alternate the vowels and the consonants. How many words of 9 letters can be formed with this alphabet?
Problem 2 N.P 17 France How many are there 9-digit numbers which the sum of figures is even ?
Problem 3 N.P 17 France A natural number is said "nice" when its written contains only odd digits. How many are there 4-digit "nice" integers ?

Send us your Math, Physics, or Chemistry Problems by mail . If the problem is interesting, we will post it on the website.
If you send a problem you earn 1 point. If you solve a problem you earn 2 points. A rating is made to reward the best players with your donations.