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Finding the Fourth Proportional to 420, 579.60 and 282

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Solution

The fourth proportional to 420, 579.60 and 282 is: 389.16

Step by Step Solution

  1. Step 1: Write the proportion equation
    420 : 579.60 = 282 : x
  2. Step 2: Convert to fraction form
    420/579.60 = 282/x
  3. Step 3: Cross multiply
    420x = 579.60 × 282
  4. Step 4: Simplify right side
    420x = 163,447.20
  5. Step 5: Solve for x
    x = 163,447.20/420
  6. Step 6: Final answer
    x = 389.16

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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.