Tech World is a company which manufactures mobile phone handsets. From its past experiences, Tech World has realised that whenever a new design engineer is employed, there is a learning curve with a 75% learning rate which exists for the first 15 jobs.

A new design engineer has just completed his first job in five hours.

Note: At the learning rate of 75%, the learning factor (b) is equal to –0·415.

How long would it take the design engineer to complete the sixth job?

A. 2·377 hours
B. 1·442 hours
C. 2·564 hours
D. 5 hours