Correct Answer - Option 2 :

Only II

**Given: **

Average weight of n employees = 70 kg

Average weight of 10 employees who leave = 73 kg

Average weight of 5 employees who join = 70 kg

Difference in average weight = 0.4 kg

**Formula Used: **

Average = Sum of values/Number of values

**Calculation:**

Sum of the weight of 10 employees who leave/10 = 73 kg

⇒ Sum of the weight of 10 employees who leave = 730 kg

Sum of the weight of 5 employees who join/5 = 70 kg

⇒ Sum of the weight of 5 employees who join = 350 kg

Sum of the weight of n employees/n = 70 kg

⇒ Sum of the weight of n employees = 70n kg

∵ 10 employees leave and 5 join

∴ Number of employees left = n – 5

Sum of the weight of n – 5 employees/(n – 5) = 70 – 0.4

⇒ Sum of the weight of n – 5 employees = 69.6(n – 5)

⇒ 70n – 730 + 350 = 69.6n – 348

⇒ 0.4n = 32

⇒ **n = 80 **kg

I. 73 employees are left

80 – 10 + 5 = 75

⇒ I is not correct

II. n is a multiple of 16

80 = 5 × 16

⇒ II is correct

III. 70 < n < 80

⇒ 70 < n = 80

⇒ III is not correct

**∴**** Only II is correct**