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Finding the Fourth Proportional to 815.12, 1,217.38 and 669.20

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Solution

The fourth proportional to 815.12, 1,217.38 and 669.20 is: 999.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    815.12 : 1,217.38 = 669.20 : x
  2. Step 2: Convert to fraction form
    815.12/1,217.38 = 669.20/x
  3. Step 3: Cross multiply
    815.12x = 1,217.38 × 669.20
  4. Step 4: Simplify right side
    815.12x = 814,670.70
  5. Step 5: Solve for x
    x = 814,670.70/815.12
  6. Step 6: Final answer
    x = 999.45

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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.