A man engaged a servant on the condition that he would pay him Rs. 90 and a turban after service of one year. he served only for nine months and received the turban and an amount of Rs. 65. The price of turban is: 

Find the value of $$ {1\over{2×5}}+{1\over {5×8}}+{1\over {8 × 11}}+......{1\over {23 × 26}}=?$$

Four numbers, when arranged in ascending order, are w, x, y and z. The average of the smallest three numbers is 25.5 while the average of the largest three was 29.5. What is the range of the data?

A number x when divided by 289 leaves 18 as the remainder. The same number when divided by 17 leaves y as a remainder. The value of y is 

Sum of two numbers is thrice their difference. Their ratio is 

Find the average of all prime numbers from 1 to 20?

The difference between the sum of four consecutive odd numbers and three consecutives even numbers together is 20. Also, the largest even number is 5 more than the largest odd number. What is the sum of the smallest odd number and the smallest even number?

If the arithmetic means of 3a and 4b is greater than 50, and a is twice b, then the smallest possible integer value of a is: