Question 809956
First convert each percentage to decimal form. You do this by dividing the percentage by 100. So for instance 10% = 10/100 = 0.10 and 85% = 85/100 = 0.85, I'm sure you get the idea.


Then you multiply each decimal form of the percentages together in pairs. So for test 1, we have 80% of 2.5% which means we do 0.80*0.025 = 0.02


For test 2, we have 100% of 2.5% ---> 1.00 * 0.025 = 0.025


Test 3: 65% of 5% = 0.65 * 0.05 = 0.0325


Test 4: 70% of 10% = 0.70 * 0.10 = 0.07


Test 5: 65% of 25% = 0.65*0.25 = 0.1625


Test 6: 80% of 10% = 0.80 * 0.10 = 0.08


Test 7: 70% of 15% = 0.70 * 0.15 = 0.105



Now add up the products we got above


0.02 + 0.025 + 0.0325 + 0.07 + 0.1625 + 0.08 + 0.105 = 0.495


So far, we have 0.495


Now let's say that 'x' is the exam score. 30% of this score is 0.30x


Add this to 0.495 to get 0.30x + 0.495


And let's say we want to get a 70% or higher, so make 0.30x + 0.495 larger than 0.70 to get


0.30x + 0.495 > 0.70


0.30x > 0.70 - 0.495


0.30x > 0.205


x > 0.205/0.30


x > 0.6833


So that means you need to score a 68.33% (roughly) on the exam (or higher) to get a 70% or higher overall grade.


Note: replace 0.70 in the original inequality with whatever you want (say 0.80) if you want to bump up the passing threshold.