the average marks of a,b,c is 33 while the average marks of b,c,d is 37. if a obtain 30 marks find the marks obatined by d

a + b + c/3 = 33

a + b + c = 99

a = 30

30 + b + c = 99

b + c = 69..................(1)

b + c + d/3 =37

b + c +d = 111

69 + d = 111(by 1)

d = 42

MEAN OF a,b,c=a+b+c/3

33=30+b+c/3

b+c=99-30

b+c=69

mean of b,c,d=b+c+d/3

37*3=69+d/

111-69=d

d=42

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