Let total journey = y km
Total time taken = time taken during 60% of distance + time taken during 20% of distance + time taken in remaining distance
= [( 60y / 100 ) / 30] + [( 20y / 100 ) / 20] + [( 20y / 100 ) / 10]
= ( y / 50 + y / 100 + y / 50 )hrs
= y/20 hrs.

Correct Option: A

Let total journey = y km
Total time taken = time taken during 60% of distance + time taken during 20% of distance + time taken in remaining distance
= [( 60y / 100 ) / 30] + [( 20y / 100 ) / 20] + [( 20y / 100 ) / 10]
= ( y / 50 + y / 100 + y / 50 )hrs
= y/20 hours.

Average speed = total distance traveled / total time taken.
= [y / ( y/20 )] km/hr
=20 km/hr.

Let total journey be y km.
From question y/35 - y/40= 15/60

Correct Option: C

Let total journey be y km.
From question y/35 - y/40= 15/60
⇒ y = ( 35 x 40 )/ ( 4 x 5 ) = 70
∴ Total Journey = 70 km

New sum of number = previous sum - 26 + 36
=10 x 15 - 26 + 36
= 160

Correct Option: C

New sum of numbers = previous sum - 26 + 36
=10 x 15 - 26 + 36
= 160
∴ Correct Average = 160 / 10 = 16.

Seventh Result = sum of first 7 results + sum of last 7 results - sum of all 13 results.

Correct Option: A

Seventh Result = sum of first 7 results + sum of last 7 results - sum of all 13 results.
⇒ Seventh Result = (7 x 63) + (7 x 70) - (13 x 68 )
=47

Thirteenth Result = sum of all 25 results - sum of first 12 results - sum of last 12 results.

Correct Option: C

Thirteenth Result = sum of all 25 results - sum of first 12 results - sum of last 12 results.
= 25 x 18 - 12 x 14 – 12 x 17
=78