Which has a greater dipole: chloroform (CHCl3) or trichlorofluoromethane (CCl3F)?
Imagine a $\ce{CHCl3}$ molecule and a $\ce{CFCl3}$ molecule fixed with the carbon atom of each molecule at the origin of a three-dimensional coordinate system. Select the two coordinate systems such that the hydrogen atom of the $\ce{CHCl3}$ molecule and the fluorine atom of the $\ce{CFCl3}$ molecule both lie on the $z$-axis above the origin, and let $u_z$ be the $z$ unit vector. If the four single covalent bonds of each molecule are symmetrical (here, tetrahedral), then it follows that the net vector sum of any four vectors that are equal in magnitude and are directed in the four directions from the origin to each non-carbon atom will be the zero vector. In both molecules, the net vector dipole moment arising from the three $\ce{C-Cl}$ bonds will equal the dipole moment of a single $\ce{C-Cl}$ bond with the chlorine atom in the direction of $-u_z$ from the carbon atom.

Assuming arguendo that the dipole moment of each bond is proportional to the difference in electronegativity of the two atoms between which that bond lies (on the Pauling Electronegativity Scale, hydrogen rates a $2.1$, carbon rates a $2.5$, chlorine rates a $3.0$, and fluorine rates a $4.0$), then to find the dipole moment of the $\ce{CHCl3}$ molecule, we add the vector dipole moment of the $\ce{C-H}$ bond ($[(2.1 - 2.5) \cdot u_z]$, or $-0.4 u_z$) to the vector dipole moment of the $\ce{C-Cl}$ bond ($[(3.0 - 2.5) \cdot (-u_z)]$, or $-0.5 u_z$), obtaining $[(-0.4 u_z) + (-0.5 u_z)]$ or $-0.9 u_z$.

To find the dipole moment of the $\ce{CFCl3}$ molecule, we add the vector dipole moment of the $\ce{C-F}$ bond ($[(4.0 - 2.5) \cdot u_z]$, or $1.5 u_z$) to the vector dipole moment of the $\ce{C-Cl}$ bond ($[(3.0 - 2.5) \cdot (-u_z)]$, or $-0.5 u_z$), obtaining $[(1.5 u_z) + (-0.5 u_z)]$ or $1.0 u_z$.

One might thus conclude that the dipole moment of $\ce{CFCl3}$ might be some ten percent larger in magnitude (as proportional to 1.0) than is that of $\ce{CHCl3}$ (as proportional to 0.9).