Perform the following calculations with the correct number of significant figures. (b) 5.1125 + 0.67 + 3.2

Multiply 4.079 x 10² m by 0.057 x 10⁻¹ m , taking into account significant figures.

For small angles θ, the numerical value of sin θ is approximately the same as the numerical value of tan θ. Find the largest angle for which sine and tangent agree to within two significant figures.

An average family of four uses roughly 1200 L (about 300 gallons) of water per day (1L = 1000 cm³). How much depth would a lake lose per year if it covered an area of 60 km² with uniform depth and supplied a local town with a population of 40,000 people? Consider only population uses, and neglect evaporation, rain, creeks and rivers.