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Finding the Fourth Proportional to 869.40, 1,220.40 and 869.40

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Solution

The fourth proportional to 869.40, 1,220.40 and 869.40 is: 1,220.40

Step by Step Solution

  1. Step 1: Write the proportion equation
    869.40 : 1,220.40 = 869.40 : x
  2. Step 2: Convert to fraction form
    869.40/1,220.40 = 869.40/x
  3. Step 3: Cross multiply
    869.40x = 1,220.40 × 869.40
  4. Step 4: Simplify right side
    869.40x = 1,061,015.76
  5. Step 5: Solve for x
    x = 1,061,015.76/869.40
  6. Step 6: Final answer
    x = 1,220.40

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.40) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.