1. Use Newton’s law of cooling

For a body cooling in surroundings of constant temperature $T_s$, we have

$T - T_s = (T_0 - T_s)e^{-kt}$

where:

• $T_0$ = initial temperature of body
• $T_s$ = surrounding temperature
• $k$ = cooling constant

Here,

$T_s = 16^\circ \mathrm{C}$

2. Apply the data for the first 4 minutes

Initially,

$T_0 = 40^\circ \mathrm{C}$

So excess temperature above surroundings is

$40 - 16 = 24^\circ \mathrm{C}$

After 4 minutes, temperature becomes

$24^\circ \mathrm{C}$

So excess temperature is

$24 - 16 = 8^\circ \mathrm{C}$

Thus in 4 minutes, the excess temperature becomes

$24 \to 8$

So it is multiplied by

$\frac{8}{24} = \frac{1}{3}$

Hence, every 4 minutes,

$T - 16$ gets multiplied by $\frac{1}{3}$.

3. Find temperature after the next 4 minutes

At the end of first 4 minutes, excess temperature is

$8^\circ \mathrm{C}$

After the next 4 minutes, it becomes

$8 \times \frac{1}{3} = \frac{8}{3}$

Therefore the body temperature then will be

$T = 16 + \frac{8}{3} = \frac{48+8}{3} = \frac{56}{3}^\circ \mathrm{C}$

4. Check options

• A: $\frac{28}{3}^\circ \mathrm{C}$
• B: $\frac{56}{3}^\circ \mathrm{C}$ ✅
• C: $\frac{42}{3}^\circ \mathrm{C}$
• D: $\frac{14}{3}^\circ \mathrm{C}$

So the correct option is B.