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Finding the Fourth Proportional to 715.20, 986.98 and 420.40

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Solution

The fourth proportional to 715.20, 986.98 and 420.40 is: 580.15

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.20 : 986.98 = 420.40 : x
  2. Step 2: Convert to fraction form
    715.20/986.98 = 420.40/x
  3. Step 3: Cross multiply
    715.20x = 986.98 × 420.40
  4. Step 4: Simplify right side
    715.20x = 414,926.39
  5. Step 5: Solve for x
    x = 414,926.39/715.20
  6. Step 6: Final answer
    x = 580.15

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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.