4.7:78

The ratio 4.7:78 can be simplified by dividing both numbers by their greatest common divisors (GCD). However, because 4.7 is a decimal and 78 is an integer, it can be easier to convert 4.7 to an integer by multiplying both sides of the ratio by 10, which gives us:

\( 4.7 \times 10 : 78 \times 10 \) \( 47 : 780 \)

Next, we can simplify this further by finding the GCD of 47 and 780. Since 47 is a prime number, we can check for divisibility:

1. 47 does not divide 780 evenly (780 ÷ 47 ≈ 16.6).

Thus, the GCD is 1, meaning the ratio cannot be simplified further.

Therefore, the simplest form of the ratio 4.7:78 is:

47:780.