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Finding the Fourth Proportional to 840.38, 1,158.69 and 643.58

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Solution

The fourth proportional to 840.38, 1,158.69 and 643.58 is: 887.35

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.38 : 1,158.69 = 643.58 : x
  2. Step 2: Convert to fraction form
    840.38/1,158.69 = 643.58/x
  3. Step 3: Cross multiply
    840.38x = 1,158.69 × 643.58
  4. Step 4: Simplify right side
    840.38x = 745,709.71
  5. Step 5: Solve for x
    x = 745,709.71/840.38
  6. Step 6: Final answer
    x = 887.35

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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.