4. Elaine spun this spinner 80 times and graphed her results.

Step 1 ：First, we need to find the possible outcomes that result in a two-digit even number. Since all the section numbers on Spinner II are odd, Spinner I must give an even number in order for the product to be even.

Step 2 ：The possible outcomes are: \((2,5)\), \((2,7)\), \((2,9)\), \((4,3)\), \((4,5)\), \((4,7)\), and \((4,9)\).

Step 3 ：There are a total of 20 equally likely outcomes, as there are 4 sections on Spinner I and 5 sections on Spinner II: \(4 \times 5 = 20\).

Step 4 ：Now, we can calculate the probability of obtaining a two-digit even number by dividing the number of desired outcomes by the total number of outcomes: \(\frac{7}{20}\).

Step 5 ：\(\boxed{\frac{7}{20}}\) is the probability of obtaining a two-digit even number.