Let the time taken by Josie to climb a flight of stairs be x,
then the time taken by Josie to cross the landing is 2x

If ___ is the landing and | is flight of stairs then the stair-landing looks like this

|___|___|___|___|___|___|

To climb 7 flights of stairs, you need to cross 6 landings.
Time taken by Josie to climb 7 flights of stairs is equal to 7*x = 7x
Time taken by Josie to cross 6 landings is equal to 6*2x = 12x
Total time taken = 12x+7x = 19x = 13.3
19x = 13.3 => 19x = 19*0.7 => x =0.7

To climb 10 flights of stairs, you need to cross 9 landings.
Time taken by Josie to climb 10 flights of stairs is equal to 10*x = 10x
Time taken by Josie to cross the 9 landings is equal to 9*2x = 18x
Total time taken = 10x+18x = 28x = 28*0.7 = 19.6

IMO Answer : D

Good grief, Josie must weigh 500 pounds. Can you imagine taking over 13 minutes to climb seven flights of stairs?

Also, if she takes twice as long to climb a flight of stairs, shouldn't the following be switched?

neelgandham wrote:Let the time taken by Josie to climb a flight of stairs be x,
then the time taken by Josie to cross the landing is 2x

nice one but getting 19.28 or so. but this answer is not among choices.

user123321

user123321 wrote:nice one but getting 19.28 or so. but this answer is not among choices.

user123321

Yeah that's what I was getting too.

Same reasoning as 'neelgandham' but the times reversed,

7*(2x) + 6*(x) = 13.3

x = 0.665

now, 10*(2x) + 9*(x) = 29*x = 19.285 mins (or) 19 mins 17 secs.

Both aren't there in the options though!.

I stand corrected Thanks for letting me know