Jambmaths question:
The mean of seven numbers is 96. If an eight number is added, the mean becomes 112. Find the eighth number.
Option A:
126
Option B:
180
Option C:
216
Option D:
224
Jamb Maths Solution:
Mean of seven numbers =${{\overline{x}}_{7}}=96$
Total summation of the 7 numbers$=96\times 7=672$
Mean of the eight numbers = ${{\overline{x}}_{8}}=112$
Total summation of the 7 numbers$=112\times 8=896$
The 8th number is 892 – 672 =224
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