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Finding the Fourth Proportional to 786.30, 1,178.10 and 420.72

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Solution

The fourth proportional to 786.30, 1,178.10 and 420.72 is: 630.36

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.30 : 1,178.10 = 420.72 : x
  2. Step 2: Convert to fraction form
    786.30/1,178.10 = 420.72/x
  3. Step 3: Cross multiply
    786.30x = 1,178.10 × 420.72
  4. Step 4: Simplify right side
    786.30x = 495,650.23
  5. Step 5: Solve for x
    x = 495,650.23/786.30
  6. Step 6: Final answer
    x = 630.36

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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.