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Finding the Fourth Proportional to 856.80, 1,285.20 and 638.10

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Solution

The fourth proportional to 856.80, 1,285.20 and 638.10 is: 957.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.80 : 1,285.20 = 638.10 : x
  2. Step 2: Convert to fraction form
    856.80/1,285.20 = 638.10/x
  3. Step 3: Cross multiply
    856.80x = 1,285.20 × 638.10
  4. Step 4: Simplify right side
    856.80x = 820,086.12
  5. Step 5: Solve for x
    x = 820,086.12/856.80
  6. Step 6: Final answer
    x = 957.15

Related Problems

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Half scale
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Double scale
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Similar ratio
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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.