If 1+2+3+...+n = λ then value of 1³+2³+3³+...+n³ = ?

How many two digit numbers are divisible by 13

12 men working for 8 hours a day can complete a work in 90 days. How many days will it take if 8 men working for 12 hours a day to complete the same work

Mean of 5 numbers is 27. If one number is excluded their mean is 25. Find the excluded number.

Which of the following statement(s) is/are true statements(s)

1. All squares are rhombuses also
2. All parallelograms are rectangles also
3. All parallelograms are quadrilaterals also 
4. All trapeziums are rhombuses also

If the price of gold increased by 20% on Monday and decreased by 20% on Tuesday then by what percentage is Tuesday's price higher or lower than the initial price of that week