The mean of 4 numbers is 8 when a 5th number is added the mean becomes 10, what is the 5th number?
Ok, so firstly let's think about what the mean means? Add all the numbers together and then divide by the total number of values we have.So, that means with the 4 numbers we currently have the total divided by 4 = 8.( ?+ ?+ ?+?) / 4 = 8 That means the total at the moment is 8 x 4 which = 32. We don't need to know what the individual are, but the total is very important and will help us answer the second part of this question. So, now we have the total , 32 we can think about how we can create an equation for the mean when we have 5 numbers:(32 + x)/5= 10 therefore if we multiply both sides by 5.. we will get the equation 32+ x = 50 therefore if we subtract 32 from both sides x = 18
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