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Finding the Fourth Proportional to 810.72, 1,215.48 and 420.54

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Solution

The fourth proportional to 810.72, 1,215.48 and 420.54 is: 630.50

Step by Step Solution

  1. Step 1: Write the proportion equation
    810.72 : 1,215.48 = 420.54 : x
  2. Step 2: Convert to fraction form
    810.72/1,215.48 = 420.54/x
  3. Step 3: Cross multiply
    810.72x = 1,215.48 × 420.54
  4. Step 4: Simplify right side
    810.72x = 511,157.96
  5. Step 5: Solve for x
    x = 511,157.96/810.72
  6. Step 6: Final answer
    x = 630.50

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Double scale
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1.5x scale

Why These Related Problems?

These problems maintain the same ratio (1.50) or explore similar proportional relationships. Practicing with related ratios helps build understanding of proportional relationships.