Determine if 7, 42, 13, 78 are in proportion.

The correct answer is Yes

7:42 = $\dfrac{7}{42}$ = $\dfrac{1}{6}$

13:78 = $\dfrac{13}{78}$ = $\dfrac{1}{6}$

∴ 7:42 = 13:78
Hence 7, 42, 13, 78 are in proportion.