An ordinary egg can be approximated as a 5.5- cm diameter sphere whose properties are roughly k = 0.6 W/m·k and α = 0.14 × 10-6 m2 /s. The egg is initially at a uniform temperature of 4°C and is dropped into boiling water at 97°C.

Taking the convection heat transfer coefficient to be h = 1400 W/m2 ·K, determine how long it will take for center of the egg to reach 70°C.