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Finding the Fourth Proportional to 856.38, 1,177.87 and 690.21

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Solution

The fourth proportional to 856.38, 1,177.87 and 690.21 is: 949.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    856.38 : 1,177.87 = 690.21 : x
  2. Step 2: Convert to fraction form
    856.38/1,177.87 = 690.21/x
  3. Step 3: Cross multiply
    856.38x = 1,177.87 × 690.21
  4. Step 4: Simplify right side
    856.38x = 812,977.65
  5. Step 5: Solve for x
    x = 812,977.65/856.38
  6. Step 6: Final answer
    x = 949.32

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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.