Students 83149

There are 30 students in the class. Five had a mark three — other twos and ones. The average grade was 1.9. How many students got mark one?

Correct answer:

a =  8

Step-by-step explanation:

a+b+c=30 c=5  1.9 = 301 a+2 b+3 c  1.9   30 = a+2b+3 5 57 = a+2b+15 42 = a+2b  42=a+2b a+b=25  42=a+2 b a+b=25  a+2b=42 a+b=25  Row2Row1Row2 a+2b=42 b=17  b=117=17 a=422b=422 17=8  a=8 b=17   Verifying Solution:  n=a+b+c=8+17+5=30 μ=a+b+c1 a+2 b+3 c=8+17+51 8+2 17+3 5=1019=1109=1.9



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