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Finding the Fourth Proportional to 785.40, 1,085.90 and 688.20

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Solution

The fourth proportional to 785.40, 1,085.90 and 688.20 is: 951.51

Step by Step Solution

  1. Step 1: Write the proportion equation
    785.40 : 1,085.90 = 688.20 : x
  2. Step 2: Convert to fraction form
    785.40/1,085.90 = 688.20/x
  3. Step 3: Cross multiply
    785.40x = 1,085.90 × 688.20
  4. Step 4: Simplify right side
    785.40x = 747,316.38
  5. Step 5: Solve for x
    x = 747,316.38/785.40
  6. Step 6: Final answer
    x = 951.51

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Double scale
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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.