To calculate the average speed in 2 trips

Question

A question as below:

A man initially travels 80 km at 32 km/hr and then the next 160 km at 40 km/hr. The average speed for the first 160 km of the tour is:

A. 25 km/hr

B. 34.2 km/hr

C. 35.56 km/hr

D. 40 km/hr

E. 44.2 km/hr

Here is how I calculate it:

Time1 = 80/32 ≈ 2.56 hour

Time2 = 160/40 = 4 hour

Average speed for the first 160 km is: 160/ (2.56 + 2) ≈ 35.07 (2.56 hours spent on the first 80km and 2 hours spent on the second 80km)

It’s close to the answer C but not exactly? Am I doing it the right way?

Thank you.

Answer 1

$80/32=2.5$, not $2.56$. Then you'll get C. [C]heers.

Answer 2

hint : the time should not be total time of the journey but it should be the time in which you journey first 160KM of total ( 160 + 80 ).