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Finding the Fourth Proportional to 1,278.32, 1,915.65 and 661.77

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Solution

The fourth proportional to 1,278.32, 1,915.65 and 661.77 is: 991.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,278.32 : 1,915.65 = 661.77 : x
  2. Step 2: Convert to fraction form
    1,278.32/1,915.65 = 661.77/x
  3. Step 3: Cross multiply
    1,278.32x = 1,915.65 × 661.77
  4. Step 4: Simplify right side
    1,278.32x = 1,267,719.70
  5. Step 5: Solve for x
    x = 1,267,719.70/1,278.32
  6. Step 6: Final answer
    x = 991.71

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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.