Final answer:
To find the average of all seven numbers, calculate the sum of both groups of numbers and divide by the total number of values.
Step-by-step explanation:
To find the average of all seven numbers, we need to first calculate the total sum of the numbers. Let's call the four numbers with an average of 80 as A, B, C, and D, and the three other numbers with an average of 40 as E, F, and G. We can find the sum of A, B, C, and D by multiplying the average by the number of values, which is 80 * 4 = 320. Similarly, the sum of E, F, and G is 40 * 3 = 120. Now, we can find the sum of all seven numbers by adding the two sums: 320 + 120 = 440. Finally, to find the average of all seven numbers, divide the sum by the number of values, which is 440 / 7 = 62.86 (rounded to two decimal places).