Average Practice Test 6

Question : 31 of 40

Marks: +1, -0

The arithmetic mean of the scores of a group of students in a test was 52. The brightest 20% of them secured a mean score of 80 and the dullest 25% a mean score of 31. The mean score of remaining 55% is:

54.6 approx.
51.4 approx.
50
45

Validate

Solution:

Let the total number of students be 100 and mean score of remaining 55% be x, then,

{20 ×80+ 25× 31+ 55×x}/100=52

⇒ 55x = 5200 - 2375

∴ x = 2825/55 =51.36≈ 51.4

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