Question

complete the following ....5,15,50,120,235,405,? options (a) 725 (b) 740 (c) 644 (d)640

Answer 1

(B)740 is right option

This is an example of harmonic series in which you will find ratio and difference to find consecutive numbers

You can clearly see The difference between the first term (5)and 2nd term (15) is 15-10=10. The difference between the 2nd term and 3rd term is 50-15=35.

Also, the difference between the 3rd and 4th number is120-50= 70

Also, the difference between the 4tg and 5th number is235-120=115

And finally the difference between the 5th and 6th number is405-235=170

In this series you can clearly see that consecutive number  is almost twice  of the previous number and difference between two numbers is  round about 35  

405*2=810-(35*2)

810-70=740  is right answer