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Finding the Fourth Proportional to 839.38, 1,158.42 and 485.40

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Solution

The fourth proportional to 839.38, 1,158.42 and 485.40 is: 669.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    839.38 : 1,158.42 = 485.40 : x
  2. Step 2: Convert to fraction form
    839.38/1,158.42 = 485.40/x
  3. Step 3: Cross multiply
    839.38x = 1,158.42 × 485.40
  4. Step 4: Simplify right side
    839.38x = 562,297.07
  5. Step 5: Solve for x
    x = 562,297.07/839.38
  6. Step 6: Final answer
    x = 669.90

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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.