There is a group of 11 people namely: A1, A2, A3, …, A11. The number of balls with A1 through A11 in that order is in arithmetic progression. If the number of balls with A1, A3, A5, A7, A9 and A11 is equal to 72, what is the number of balls with A1, A6 and A11 put together?
Calculate the sum of all even factors of 420.
A REAL test contains 3 sections: QA, VA and DI. A student taking the test has to attempt at least one section. When the data of test takers was assimilated, it showed that 74% of students attempted QA, 91% attempted VA and 77% attempted DI section. What could be the minimum percentage of students who attempted all the three-sections?
How many numbers smaller than 2*10^8 and are divisible by 3 can be written by means of the digits 0,1 and 2.(excluding single digit and double digit numbers?
How many four-digit numbers divisible by 9 can be formed by using exactly two distinct digits?