Quantitative Aptitude - Arithmetic Ability Questions

The mean of 12 observations is 15. One more observation is included and the new mean becomes 16. The 13th observation is

The line passing through the point (5,a) and point (4,3) is perpendicular to the line x - 6y = 8. What is the value of 'a'?

D and E are points on side AB and AC of ΔABC. DE is parallel to BC. If AD:DB = 2:5 and area of ΔABC is 98 cm sq, what is the area (in sq cm) of quadrilateral BDEC?

If a-1a=1, then a2 + 1a2 ?

If a + b = 10 and ab- 13 = -ba - 11, then what is the value of 3ab + 4a2 + 5b2 ?

Among three numbers , second is twice the first and also thrice the third . If the average of the three numbers is 33 , then the largest number is

The sum of three numbers is 2, the 1st number is 1/2 times the 2nd number and the 3rd number is 1/4 times the 2nd number. The 2nd number is

The base of a prism is in the shape of an equilateral triangle. If the perimeter of the base is 18 cm and the height of the prism is 20 cm, then what is the volume (in cm3) of the prism?