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Finding the Fourth Proportional to 1,857.40, 2,780.70 and 1,128.40

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Solution

The fourth proportional to 1,857.40, 2,780.70 and 1,128.40 is: 1,689.32

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,857.40 : 2,780.70 = 1,128.40 : x
  2. Step 2: Convert to fraction form
    1,857.40/2,780.70 = 1,128.40/x
  3. Step 3: Cross multiply
    1,857.40x = 2,780.70 × 1,128.40
  4. Step 4: Simplify right side
    1,857.40x = 3,137,741.88
  5. Step 5: Solve for x
    x = 3,137,741.88/1,857.40
  6. Step 6: Final answer
    x = 1,689.32

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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.