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Finding the Fourth Proportional to 1,187.40, 1,638.40 and 690.02

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Solution

The fourth proportional to 1,187.40, 1,638.40 and 690.02 is: 952.10

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,187.40 : 1,638.40 = 690.02 : x
  2. Step 2: Convert to fraction form
    1,187.40/1,638.40 = 690.02/x
  3. Step 3: Cross multiply
    1,187.40x = 1,638.40 × 690.02
  4. Step 4: Simplify right side
    1,187.40x = 1,130,528.77
  5. Step 5: Solve for x
    x = 1,130,528.77/1,187.40
  6. Step 6: Final answer
    x = 952.10

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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.