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Finding the Fourth Proportional to 645.40, 890.06 and 421.24

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Solution

The fourth proportional to 645.40, 890.06 and 421.24 is: 580.92

Step by Step Solution

  1. Step 1: Write the proportion equation
    645.40 : 890.06 = 421.24 : x
  2. Step 2: Convert to fraction form
    645.40/890.06 = 421.24/x
  3. Step 3: Cross multiply
    645.40x = 890.06 × 421.24
  4. Step 4: Simplify right side
    645.40x = 374,928.87
  5. Step 5: Solve for x
    x = 374,928.87/645.40
  6. Step 6: Final answer
    x = 580.92

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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.