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Finding the Fourth Proportional to 860.76, 1,291.14 and 428.22

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Solution

The fourth proportional to 860.76, 1,291.14 and 428.22 is: 642.33

Step by Step Solution

  1. Step 1: Write the proportion equation
    860.76 : 1,291.14 = 428.22 : x
  2. Step 2: Convert to fraction form
    860.76/1,291.14 = 428.22/x
  3. Step 3: Cross multiply
    860.76x = 1,291.14 × 428.22
  4. Step 4: Simplify right side
    860.76x = 552,891.97
  5. Step 5: Solve for x
    x = 552,891.97/860.76
  6. Step 6: Final answer
    x = 642.33

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.