Quantitative Aptitude - Arithmetic Ability Questions

A series is given, with one number missing. Choose the correct alternative from the given ones that will complete the series.

-7.5, 15, -30, 60, ? , 240

In a quadrilateral PQRS, l_S= 90°. A circle (o, r) touches the sides PQ, QR, RS and SP at A, B, C and D respectively. If QR= 38 cm, RS = 25 cm and QA = 27 cm, find 'r'.

The ratio of present ages of Ramya and Saurabh is 8:7. After 10 years the ratio of their ages will be 12:11. What is Ramya's present age?

Due to inclement weather, an air plane reduced its speed by 300 Km/ hr, and reached the destination of 1200 km late by 2hrs. Then the schedule duration of the flight was.

The average of 9 observations was found to be 35. Later on, it was detected that an observation 81 was misread as 18. The correct average of the observations is

The least number which when divides 37044, gives the result a perfect cube, is:

Find k, if the line 4x - y = 1 is perpendicular to the line 5x - ky = 2?

If a - b = -1 and ab = 6, then what is the value of a3- b3?