Usha left home at 11.40 a.m. and drove towards the province. 2 hours later, her older sister left their home and drove towards the same province at 92 km/h. When the older sister reached the province at 4.40 p.m., Usha had another 2 km to travel. What was Usha’s average speed? Express your answer in mixed number.
Time that the Usha's older sister started driving = 1.40 p.m.
Duration that Usha's older sister drove from 1.40 p.m. to 4.40 p.m. = 3 h

Distance that Usha's older sister travelled
= 3 x 92
= 276 km

Distance that Usha travelled by the time her older sister reached the city
= 276 - 2
= 274 km

Time that Usha took to travel 274 km = 5 h

Usha's average speed
= 274 ÷ 5
= 54⁴₅ km/h

Answer(s): 54⁴₅ km/h