The table below shows the number of books read by each pupil in a class of 30 pupils. One of the numbers in the table is covered by an ink blot.
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| Number of books read by each pupil | 0 | 8 | ?? |
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| Number of pupils | 10 | 15 | 5 |
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The average number of books read by the pupils in the class is 6.
What is the number covered by the ink blot?
30 x 6 = 180
15 x 8 = 120
180 - 120 = 60
60 ÷ 5 = 12
It is 12.
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As appeared in PSLE 2010 exam:
ReplyDeleteThe table below shows the number of books read by each pupil in a class of 30 pupils. One of the numbers in the table is covered by an ink blot.
Table:
4 columns x 2 rows.
Start from left hand side (1st row),"Number of books read by each pupil" and followed by data: 0, 8, stained with ink blot.
2nd row," Number of pupils" and followed by data: 10, 15, 5
The average number of books read by the pupils in the class is 6.
What is the number covered by the ink blot?