| The average weight of 15 girls was recorded as 54 kg. If the weight of the teacher was added, the average increased by 2 kg. What was the teacher's weight? |
A) 75 kg
B) 95 kg
C) 78 kg
D) 86 kg
E) None of these
Correct Answer: D
Solution :
| \[\frac{\sum\limits_{i=1}^{15}{{{x}_{i}}}}{15}=54\]\[\Rightarrow \]\[\sum\limits_{i=1}^{15}{{{x}_{i}}=54\times 15}\] |
| According to the question, |
| \[\sum\limits_{i=1}^{16}{{{x}_{i}}=\sum\limits_{i=1}^{15}{{{x}_{i}}}+{{x}_{16}}=16\times 56}\] |
| \[\Rightarrow \] \[{{x}_{16}}=56\times 16-\sum\limits_{i=1}^{15}{{{x}_{i}}}\] |
| \[=56\times 16-54\times 15=86\,\,kg\] |
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