Solution
= Solution
For unbiased one-dimensional <diffusion>, the <mean squared displacement> is $\langle x^2(t)\rangle=2Dt$. With $t=n\tau$, compare this to the mutant expression:
$$
2Dn\tau=\frac16n\delta^2,\qquad D=\frac{\delta^2}{12\tau}.
$$
Therefore the mutant <diffusion coefficient> is
$$
\boxed{D=\frac{(10\,\mu\mathrm m)^2}{12(50\,\mathrm s)}
=\frac16\,\mu\mathrm m^2\mathrm s^{-1}\approx0.167\,\mu\mathrm m^2/\mathrm s}.
$$