There are 45 students is a class in which 15 are girls. Average weight

1.	There are 45 students is a class in which 15 are girls. Average weight of girls is 45 kg and of boys 52 kg. Find average weight of one student.
Answer» According to question, average weight of 15 girls = 45 kg. So, \(\bar { X }=\quad \frac { { \Sigma x }_{ i } }{ n } \) ⇒ 45 = \(\frac { { \Sigma x }_{ i } }{ 15 } \) ⇒ Σx_i = 45 × 15 = 675 Total weight of 15 girls Σx_i = 675 kg Average weight of 30 boys = 52 kg So, \(\bar { Y }=\quad \frac { { \Sigma y }_{ i } }{ 30 } \) ⇒ 52 = \(\frac { { \Sigma y }_{ i } }{ 30 } \) ⇒ Σy_i = 52 × 30 = 1560 Total weight of boys Σy_i = 1560 kg Average weight of 45 students Σx_i + Σy_i = 675 + 1560 = 2235 Average weight of one student = 2235/45 = 49.67 kg.

There are 45 students is a class in which 15 are girls. Average weight of girls is 45 kg and of boys 52 kg. Find average weight of one student.

Answer»

According to question, average weight of 15 girls

= 45 kg.

So, \(\bar { X }=\quad \frac { { \Sigma x }_{ i } }{ n } \)

⇒ 45 = \(\frac { { \Sigma x }_{ i } }{ 15 } \)

⇒ Σx_i = 45 × 15 = 675

Total weight of 15 girls Σx_i = 675 kg

Average weight of 30 boys = 52 kg

So, \(\bar { Y }=\quad \frac { { \Sigma y }_{ i } }{ 30 } \)

⇒ 52 = \(\frac { { \Sigma y }_{ i } }{ 30 } \)

⇒ Σy_i = 52 × 30 = 1560

Total weight of boys Σy_i = 1560 kg

Average weight of 45 students

Σx_i + Σy_i = 675 + 1560 = 2235

Average weight of one student = 2235/45

= 49.67 kg.