Question 651340
John's test scores are 95,90,83 ,x
Average test score in four tests= 90 . 
We need to find the score in the fourth test, x
Average, 90= (95+ 90+ 83+x)/4
On cross- multiplication 
 95+90+83+x= 90*4
 268+ x= 360
 x= 360-268
 x= 92, the score in the fourth test