JAMB 2021 Mathematics · Question 20

4, 16, 30, 20, 10, 14 and 26 are represented on a pie chart. Find the sum of the angles of the bisectors representing all numbers equals to or greater than 16

Options

  1. A.48o
  2. B.84o
  3. C.92o
  4. D.276o

Answer: D. 276o

Explanation written with AI and checked against the answer key

1. Analyze the question

We are given a set of numbers: 4, 16, 30, 20, 10, 14, and 26. We need to find the sum of the angles on a pie chart that represent the numbers that are 16 or greater.

2. Explain the concept

To represent data on a pie chart, we follow these steps:

  • Find the total sum of all the numbers in the data set.
  • Identify the specific values that meet the condition (in this case, ≥16\geq 16).
  • Calculate the sum of these specific values.
  • Convert to degrees: Since a full circle is 360∘360^\circ, the angle for a specific group is calculated as: $Angle=(Sum of specific valuesTotal sum)×360∘\text{Angle} = \left( \frac{\text{Sum of specific values}}{\text{Total sum}} \right) \times 360^\circ$
3. Show the solution

Step 1: Find the total sum of the numbers. Total = 4+16+30+20+10+14+264 + 16 + 30 + 20 + 10 + 14 + 26 Total = 120120

Step 2: Identify numbers ≥16\geq 16. The numbers in the set that are 16 or greater are: 16, 30, 20, and 26.

Step 3: Find the sum of these specific numbers. Sum of values ≥16=16+30+20+26\geq 16 = 16 + 30 + 20 + 26 Sum = 9292

Step 4: Calculate the corresponding angle.

Angle=(92120)×360∘\text{Angle} = \left( \frac{92}{120} \right) \times 360^\circ

Simplify the fraction: 92120=9212×36010\frac{92}{120} = \frac{92}{12} \times \frac{360}{10} (or simply divide 360 by 120 first) 360÷120=3360 \div 120 = 3 Angle=92×3\text{Angle} = 92 \times 3 Angle=276∘\text{Angle} = 276^\circ

4. Identify the answer

Comparing our result to the given options, the correct value is 276∘276^\circ.

5. Tip

When dealing with pie chart questions, always check if the total sum is a factor of 360. If it is (like 120 is here), the calculation becomes much faster because 360/120=3360/120 = 3. You simply multiply your target sum by that constant!

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