JAMB 2015 Mathematics · Question 14
The volume of a cone (s) of height 6cm and base radius 5cm is
Options
- A.157cm3
- B.155cm3
- C.175cm3
- D.145cm3
Answer: A. 157cm3
Explanation written with AI and checked against the answer key
1. Analyze the question
We are asked to calculate the volume of a cone given its height () and base radius ().
- Height () = 6 cm
- Radius () = 5 cm
- We will use (standard for JAMB calculations unless specified as ).
2. Explain the concept
The volume () of a cone is given by the formula:
Where:
- (pi) is a constant (approximately 3.142 or 22/7)
- is the radius of the circular base
- is the perpendicular height of the cone
3. Show the solution
Step 1: Substitute the values into the formula.
Step 2: Simplify the expression. First, calculate the square of the radius:
Now, substitute back:
Step 3: Perform the arithmetic. You can simplify first, which equals 2:
Step 4: Calculate the final numerical value. Using
Rounding to the nearest whole number, we get 157 cm³.
4. Identify the answer
Comparing our result to the given options, it matches option A.
5. Tip
In JAMB Mathematics, if you see in the options, leave your answer in terms of . If the options are whole numbers, use for to get the most accurate result. Also, remember that the volume of a cone is exactly one-third the volume of a cylinder with the same radius and height ().
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