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Finding the Fourth Proportional to 1,389.71, 1,918.88 and 971.12

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Solution

The fourth proportional to 1,389.71, 1,918.88 and 971.12 is: 1,340.90

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,389.71 : 1,918.88 = 971.12 : x
  2. Step 2: Convert to fraction form
    1,389.71/1,918.88 = 971.12/x
  3. Step 3: Cross multiply
    1,389.71x = 1,918.88 × 971.12
  4. Step 4: Simplify right side
    1,389.71x = 1,863,462.75
  5. Step 5: Solve for x
    x = 1,863,462.75/1,389.71
  6. Step 6: Final answer
    x = 1,340.90

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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.