Radika has marks of 75,82,90 in 3 maths test.How many marks must she obtained in the next test to have an average of 85 for the four test?
(75+82+90+X)/4 = 85. X = ?.
To find out how many marks Radika must obtain in the next test to have an average of 85 for the four tests, we can use the formula for average:
Average = Sum of all marks / Number of Tests
Let's calculate the sum of Radika's current marks:
Sum of current marks = 75 + 82 + 90 = 247
Now, we know that the average of the four tests should be 85. So, we can rearrange the formula as follows:
Sum of all marks = Average * Number of Tests
We substitute the values we know into the equation and solve for the sum of all marks:
Sum of all marks = 85 * 4 = 340
Next, we find out how many marks Radika must obtain in the next test to achieve a sum of 340 for all four tests:
Marks in the next test = Sum of all marks - Sum of current marks
Marks in the next test = 340 - 247
Marks in the next test = 93
Therefore, Radika must obtain 93 marks in the next test to have an average of 85 for all four tests.