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Finding the Fourth Proportional to 715.31, 986.90 and 420.67

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Solution

The fourth proportional to 715.31, 986.90 and 420.67 is: 580.38

Step by Step Solution

  1. Step 1: Write the proportion equation
    715.31 : 986.90 = 420.67 : x
  2. Step 2: Convert to fraction form
    715.31/986.90 = 420.67/x
  3. Step 3: Cross multiply
    715.31x = 986.90 × 420.67
  4. Step 4: Simplify right side
    715.31x = 415,152.19
  5. Step 5: Solve for x
    x = 415,152.19/715.31
  6. Step 6: Final answer
    x = 580.38

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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.