Direction (66-70): What should come in place of the question mark(?) in the following number series?

4    6    14    44  ?   892

A man starts going for morning walk every day. The distance walked by him on the first day was 2 km. Everyday he walks half of the distance walked on the previous days. What can be the maximum total distance walked by him in his life-time?

Direction : What should come in place of the question (?) in the following question.

15  34    20   ?   25    43  30

Direction : What should come in place of the question (?) in the following question.

16  8    12   30  ?    472.5

What will come in place of question mark ( ? ) in the following series?
13, 25, 61, 121, 205, ? 

What will come in place of the question mark (?) in each of the following series?

 15     12    17  10     ?    8    21     6 

If the arithmetic mean of 6, 8, 10. x, 7 is 8.the value of x will be

If a , b , c are in AP and x , y and z are in GP , then $${x^{b-c}.{y^{c-a}.z^{a-b}=?}}$$