Question

If the average weight of $6$ students is $50$ kg, that of $2$ students is $51$ kg and that of rest of $2$ students is $55$ kg, then the average weight of all the students is

• A. $61$ kg
• B. $51.5$ kg
• C. $52$ kg
• D. $51.2$ kg

Answer 1

The correct option is D $51.2$ kg

Total weight of 6 students $=6\times 50$ kg $=300$ kg
Total weight of 2 students $=2\times 51$ kg $=102$ kg
Total weight of 2 students $=2\times 55$ kg $=110$ kg
$\therefore$ Average weight of all the students $=\frac{\text{Total weight}}{\text{Number of students}}=\frac{300+102+110}{10}$ kg
$=\frac{512}{10}$ kg $=51.2$ kg