Riddles Options

[shivani]

1. Guess the next number

77 58 49 45 29 27 23

[shivani]

ayoooo Vivekah..
am getting slightly scared of u now..
u r an evil mathematician !!
ye lo ..since you love maths so much
5. A car has a journey of 78 miles to make.
The first half of the journey is uphill, and the second half downhill.
He averages 30 miles an hour to the top of the hill.
How fast must he go down the hill to average 60 miles per hour?

[vivekpm]

ayoooo Vivekah..
am getting slightly scared of u now..
u r an evil mathematician !!
ye lo ..since you love maths so much
5. A car has a journey of 78 miles to make.
The first half of the journey is uphill, and the second half downhill.
He averages 30 miles an hour to the top of the hill.
How fast must he go down the hill to average 60 miles per hour?

Though I would very much love to be one, but I am not a mathematician . At one point of time, I used to play a lot with numbers. But you seem to have a treasure of puzzles, that keep puzzling me. All good riddles

Now this one, is there a finite answer to this one? My calculations tell me that to make 60 miles/hour, he should cover the distance in 78 minutes (obviously) and by the time car reaches on the top of the hill (at 30 miles/hour), it would have taken exactly that much time (to cover 39 miles uphill at 30 miles/.hour).

So I think 60 miles/hour is impossible unless car can travel infinitely fast downhill or have a free fall with infinite acceleration, without being influenced by gravity of course. I better shut up here because I know Physics is not my cup of tea and have seen your inputs on this subject on other thread

Cheers,