<PRE><B>Question 705736</B>
4 kids score 100. The rest score at least 70.
 The average is 78. How many kids in the class.
:
let n = number of kids in the class
:
Av of 71, 72, 73 would not give me an integer solution so used 74 average
:
{{{(74(n-4) + 400)/n}}} = 78
mult both sides by n
74n - 296 + 400 = 78n
400 - 296 = 78n - 74n
104 = 4n
n = 104/4
n = 26 kids 

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