Ok, so first you know that each number is out of 50, so to find a percentage you double each number: 64,56,42,48. Now find the mean (add all numbers together and divide by the amount of numbers: 64+56+42+48=52.5. This means the average percentage of heads is 52.5. Now you just need to find 52.5% of 1,000. That's 525. So the answer is 525. Your welcome :)