Mrs Chye left home at 8 a.m. and drove towards the city. 1¹₂ hour later, Mr Chye left the house and drove at an average speed of 92 km/h towards the city. When Mr Chye reached his destination at 1 p.m., Mrs Chye was 10 km away from the city. Find Mrs Chye’s average speed in km/h. Express your answer in mixed number.
1 h = 60 min 
¹₂ h = ¹₂ x 60 = 30 min
1¹₂ = 1 h 30 min

1 h 30 min after 8 a.m. = 9.30 a.m.

Time that Mr Chye left the house = 9.30 a.m.

Time that Mr Chye took from 9.30 a.m. to 1 p.m. to reach his destination = 3 h 30 min

1 min = ¹₆₀ h
30 min = ³⁰₆₀ h = ¹₂ h
3 h 30 min = 3¹₂ h

Distance that Mr Chye drove
= 3¹₂ x 92
= 322 km

Distance that Mrs Chye drove when Mr Chye reached
= 322 - 10 
= 312 km

Time that Mrs Chye took to travel from 8 a.m. to 1 p.m. = 5 h

Mrs Chye's average speed
= 312 ÷ 5
= 62²₅ km/h

Answer(s): 62²₅ km/h