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Finding the Fourth Proportional to 830.40, 1,245.12 and 638.40

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Solution

The fourth proportional to 830.40, 1,245.12 and 638.40 is: 957.23

Step by Step Solution

  1. Step 1: Write the proportion equation
    830.40 : 1,245.12 = 638.40 : x
  2. Step 2: Convert to fraction form
    830.40/1,245.12 = 638.40/x
  3. Step 3: Cross multiply
    830.40x = 1,245.12 × 638.40
  4. Step 4: Simplify right side
    830.40x = 794,884.61
  5. Step 5: Solve for x
    x = 794,884.61/830.40
  6. Step 6: Final answer
    x = 957.23

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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.