A cylindrical tank has a capacity of 6160m3. What is the depth of the tank if the radius of its base is 28cm?

Analyze the question: We're given the volume (capacity) of a cylinder and its base radius, and we need the depth (height).

Concept: Volume of a cylinder: V = πr²h, so h = V / (πr²)

Solution:

Units issue: the capacity is in m³ but the radius is in cm. Let's try the data as written first.

Taking r = 28 m (the likely intended unit), with π = 22/7:

• r² = 28 × 28 = 784
• πr² = (22/7) × 784 = 22 × 112 = 2464
• h = 6160 / 2464 = 2.5

So h = 2.5 m.

Check with r = 28 cm literally: r = 0.28 m, so πr² = (22/7)(0.0784) = 0.2464 m². Then h = 6160 / 0.2464 = 25,000 m, which matches none of the options. So the question must have intended the radius as 28 m (a typo in the unit), and the answer is 2.5 m.

Answer: Option D (2.5 m).

Tip: Always check units first. If the working gives an absurd result (a 25 km deep tank!) and one option fits neatly with a changed unit, suspect a typo in the question. Also, when you see 28 or 7 with π, use 22/7, because the 7 cancels neatly.