Home / 870.72-1,305-431.50

Finding the Fourth Proportional to 870.72, 1,305 and 431.50

Calculator

Solution

The fourth proportional to 870.72, 1,305 and 431.50 is: 646.71

Step by Step Solution

  1. Step 1: Write the proportion equation
    870.72 : 1,305 = 431.50 : x
  2. Step 2: Convert to fraction form
    870.72/1,305 = 431.50/x
  3. Step 3: Cross multiply
    870.72x = 1,305 × 431.50
  4. Step 4: Simplify right side
    870.72x = 563,107.50
  5. Step 5: Solve for x
    x = 563,107.50/870.72
  6. Step 6: Final answer
    x = 646.71

Related Problems

Find fourth proportional to 435.36, 652.50 and 215.75
Half scale
Find fourth proportional to 1,741.44, 2,610 and 863
Double scale
Find fourth proportional to 871.72, 1,306.50 and 432.50
Similar ratio
Find fourth proportional to 1,306.08, 1,957.50 and 647.25
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.