IKMC 2027 - Grades 9-10 - Self-study SET 3 - Thematic Batch 3 Question 30

Question 30

A rectangular cuboid has base dimensions a×2a, where a is fixed. Its total surface area is 180. Which formula gives its height h?

1. $\frac{30}{a} - \frac{2}{3}a$
2. $\frac{30}{a} + \frac{2}{3a}$
3. $\frac{180}{4a^2 + 6a}$
4. $\frac{180 - 6a}{4a^2}$
5. None of the other four options is correct