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Finding the Fourth Proportional to 645.81, 891.21 and 380.19

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Solution

The fourth proportional to 645.81, 891.21 and 380.19 is: 524.66

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.81 : 891.21 = 380.19 : x
  2. Step 2: Convert to fraction form
    645.81/891.21 = 380.19/x
  3. Step 3: Cross multiply
    645.81x = 891.21 × 380.19
  4. Step 4: Simplify right side
    645.81x = 338,829.13
  5. Step 5: Solve for x
    x = 338,829.13/645.81
  6. Step 6: Final answer
    x = 524.66

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Double scale
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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.