Grades 7-8 Video Solutions 2023-2023_7-8

Video Transcription

Question 7. John has 150 coins. When he throws them on the table, 40% of them show heads, and 60% of them show tails. How many coins showing tails does he need to turn over to  have the same number of coins show heads as tails? So if we work at this problem backwards, we know we want to end up with half of the coins  being heads and half of them tails. We have 150 coins, so that means 75 coins will show heads and 75 will show tails. Now, if we take a look at what we started off with, 150 coins,  40% of them showing heads, and 60% of them showing tails, we take 40% of 150, we get 60. And if we take 60% of 150, we get 90. Now, we have to turn over enough coins that  are tails to heads to make it 75. So if we take 90 minus 75, we will get our answer, which will be B, 15.

Video Summary

John needs to turn over 15 tails. Beginning with 150 coins showing 60 heads (40% of 150) and 90 tails (60% of 150), he needs an even split of 75 heads and 75 tails. To achieve this, John must convert 15 tails to heads, resulting in the required balance.