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Finding the Fourth Proportional to 715.34, 986.90 and 420.40

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Solution

The fourth proportional to 715.34, 986.90 and 420.40 is: 579.99

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.34 : 986.90 = 420.40 : x
  2. Step 2: Convert to fraction form
    715.34/986.90 = 420.40/x
  3. Step 3: Cross multiply
    715.34x = 986.90 × 420.40
  4. Step 4: Simplify right side
    715.34x = 414,892.76
  5. Step 5: Solve for x
    x = 414,892.76/715.34
  6. Step 6: Final answer
    x = 579.99

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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.