Home / 1,287.50-1,931-628.71

Finding the Fourth Proportional to 1,287.50, 1,931 and 628.71

Calculator

Solution

The fourth proportional to 1,287.50, 1,931 and 628.71 is: 942.94

Step by Step Solution

  1. Step 1: Write the proportion equation
    1,287.50 : 1,931 = 628.71 : x
  2. Step 2: Convert to fraction form
    1,287.50/1,931 = 628.71/x
  3. Step 3: Cross multiply
    1,287.50x = 1,931 × 628.71
  4. Step 4: Simplify right side
    1,287.50x = 1,214,039.01
  5. Step 5: Solve for x
    x = 1,214,039.01/1,287.50
  6. Step 6: Final answer
    x = 942.94

Related Problems

Find fourth proportional to 643.75, 965.50 and 314.36
Half scale
Find fourth proportional to 2,575, 3,862 and 1,257.42
Double scale
Find fourth proportional to 1,288.50, 1,932.50 and 629.71
Similar ratio
Find fourth proportional to 1,931.25, 2,896.50 and 943.07
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.