Express the following in SI units : (i) 5' 6'', the average height of an Indian man. (ii) 80 miles per hour, the average speed of a roadways bus. (iii) 100 pounds, the average weight of an Indian girl. (Take 1 lb = 454 g) (iv) `-10^(@)C`, the lowest temperature in Simla. (v) 2 litres of milk, the average consumption of a family of 4 persons. (vi) 14 pounds per square inch (atmospheric pressure)

Explanation

To convert the given values into SI units, we will follow a systematic approach for each part of the question.

### Solution:

**(i) 5' 6'' (height of an Indian man)**

1. Convert feet to inches:
- 5 feet = 5 × 12 inches = 60 inches
- Total height = 60 inches + 6 inches = 66 inches

2. Convert inches to meters:
- 1 inch = 2.54 cm
- 66 inches = 66 × 2.54 cm = 167.64 cm
- Convert cm to meters: 167.64 cm = 167.64 / 100 m = 1.6764 m
- Rounding off, the height is approximately **1.68 m**.

**(ii) 80 miles per hour (average speed of a roadways bus)**

1. Convert miles to meters:
- 1 mile = 1.609 km = 1609 m
- 80 miles = 80 × 1609 m = 128720 m

2. Convert hours to seconds:
- 1 hour = 3600 seconds

3. Calculate speed in meters per second:
- Speed = Distance / Time = 128720 m / 3600 s = 35.8 m/s

**(iii) 100 pounds (average weight of an Indian girl)**

1. Convert pounds to grams:
- 1 lb = 454 g
- 100 lb = 100 × 454 g = 45400 g

2. Convert grams to kilograms:
- 45400 g = 45400 / 1000 kg = 45.4 kg

**(iv) -10°C (lowest temperature in Simla)**

1. Convert Celsius to Kelvin:
- K = °C + 273.15
- K = -10 + 273.15 = 263.15 K

**(v) 2 liters of milk (average consumption of a family of 4 persons)**

1. Convert liters to cubic decimeters:
- 1 liter = 1 dm³
- Therefore, 2 liters = 2 dm³

**(vi) 14 pounds per square inch (atmospheric pressure)**

1. Convert pounds per square inch to kilograms per square meter:
- 1 lb = 0.453592 kg
- 1 inch = 0.0254 m
- 1 in² = (0.0254 m)² = 0.00064516 m²

2. Convert 14 lb/in² to kg/m²:
- 14 lb/in² = 14 × 0.453592 kg / 0.00064516 m²
- = 14 × 0.453592 / 0.00064516 kg/m²
- ≈ 100,000 kg/m² (approximately)

### Final Answers:
1. Height: **1.68 m**
2. Speed: **35.8 m/s**
3. Weight: **45.4 kg**
4. Temperature: **263.15 K**
5. Volume: **2 dm³**
6. Pressure: **≈ 100,000 kg/m²**