MATH DOSE 9

1. 9 year ago the average age of 5 member family is 33. Now three members added in family whose  age is in ascending order increasing by 8 forms consecutive. Present average age of family is same as 9 year ago find the age of new youngest member added in family.

2. X+1/x is 10 find x³+ 1/x³

3. a²+b²=99, ab=11 find a³ +b³

4. A train covers 20 km with uniform speed. If it has been 8 km/h more than it take 10 hour less for same journey. What is the speed of train in km/h. (Answer-4)

 5. The ratio between speeds of two train is 5:7. If first train covers 300 km in 3 hour then find the speed of second train. (Answer- 140km/h)