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Finding the Fourth Proportional to 1,238.29, 1,708.90 and 678.78

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Solution

The fourth proportional to 1,238.29, 1,708.90 and 678.78 is: 936.75

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,238.29 : 1,708.90 = 678.78 : x
  2. Step 2: Convert to fraction form
    1,238.29/1,708.90 = 678.78/x
  3. Step 3: Cross multiply
    1,238.29x = 1,708.90 × 678.78
  4. Step 4: Simplify right side
    1,238.29x = 1,159,965.45
  5. Step 5: Solve for x
    x = 1,159,965.45/1,238.29
  6. Step 6: Final answer
    x = 936.75

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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.