False, because 33 is divisible by 3, but 33 is not divisible by 9.
Therefore given statement is not correct.

Malarvizhi comes to her home once in 5 days. Similarly, Karthiga and Anjalicome to their homes once in 6 days and 10 days respectively.
Therefore 5 days, 6 days, 10 days.

LCM = \(5 \times 2 \times 3\) = 30
Therefore all the three will meet again once in 30 days on 31^st of October.

Given statement
The sum of 3 prime numbers is 80.
The difference of two of them is 4.
Let the 3 prime numbers be x, y and z
x + y + z = 80 and z - y = 4
Prime numbers are
2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79
80 = 2 + 37 + 41
= z - y
= 41 - 37 = 4
Therefore x = 2, y = 37, z = 41
Ans : The 3 prime numbers are 2, 37 and 41.

Given: 40 seconds, 60 seconds and 72 seconds

LCM = \(2 \times 2 \times 5 \times 2 \times 3 \times 3\) = 360 seconds
Also given, they changed simultaneously together at 8 a.m.
Therefore 360 seconds = 6 min
⇒ 1 hour = 60 min
Therefore 8 a.m. + 6 min = 8.00 + 0.06
Time = 8.06 a.m.
After 360 seconds, therefore 8.06 a.m. will they simultaneously change together again.

Let 3 odd natural numbers are 3, 7 and 9.
Sum = 3 + 7 + 9 = 19 is odd.
This statement is true.