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Finding the Fourth Proportional to 1,020.40, 1,408.08 and 647.20

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Solution

The fourth proportional to 1,020.40, 1,408.08 and 647.20 is: 893.09

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,020.40 : 1,408.08 = 647.20 : x
  2. Step 2: Convert to fraction form
    1,020.40/1,408.08 = 647.20/x
  3. Step 3: Cross multiply
    1,020.40x = 1,408.08 × 647.20
  4. Step 4: Simplify right side
    1,020.40x = 911,309.38
  5. Step 5: Solve for x
    x = 911,309.38/1,020.40
  6. Step 6: Final answer
    x = 893.09

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.38) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.