In a class average the mark in an exam is 70. The average of students who scored below 60 is 50. The average of students who scored 60 or more is 75. If the total number of students in this class is 20, how many students scored less than 60?
Created: 5 years ago |
Updated: 4 months ago
best des
TR, TP are two tangents drawn to a bigger circle from an external point T.
we know that,
length of tangents drawn from external point to circle are equal
∴TR = TP ___(i)
Similarly TP, TQ are two tangent drawn to a smaller circle from an external point T.
Again we have TP = TQ __(ii)
From (i) & (ii), we have TR = TQ
Md Azizur Rahman
Founder of Satt
solve the equations:
x + y = 20 -------- (i)
50x + 75y = 70 x 20 ------- (ii)
So, there are 16 students who scored 60 or more.
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