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Finding the Fourth Proportional to 840.18, 1,255.45 and 641.42

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Solution

The fourth proportional to 840.18, 1,255.45 and 641.42 is: 958.45

Step by Step Solution

  1. Step 1: Write the proportion equation
    840.18 : 1,255.45 = 641.42 : x
  2. Step 2: Convert to fraction form
    840.18/1,255.45 = 641.42/x
  3. Step 3: Cross multiply
    840.18x = 1,255.45 × 641.42
  4. Step 4: Simplify right side
    840.18x = 805,270.74
  5. Step 5: Solve for x
    x = 805,270.74/840.18
  6. Step 6: Final answer
    x = 958.45

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.49) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.