Home / 678.90-1,017.45-486.30

Finding the Fourth Proportional to 678.90, 1,017.45 and 486.30

Calculator

Solution

The fourth proportional to 678.90, 1,017.45 and 486.30 is: 728.81

Step by Step Solution

  1. Step 1: Write the proportion equation
    678.90 : 1,017.45 = 486.30 : x
  2. Step 2: Convert to fraction form
    678.90/1,017.45 = 486.30/x
  3. Step 3: Cross multiply
    678.90x = 1,017.45 × 486.30
  4. Step 4: Simplify right side
    678.90x = 494,785.94
  5. Step 5: Solve for x
    x = 494,785.94/678.90
  6. Step 6: Final answer
    x = 728.81

Related Problems

Find fourth proportional to 339.45, 508.73 and 243.15
Half scale
Find fourth proportional to 1,357.80, 2,034.90 and 972.60
Double scale
Find fourth proportional to 679.90, 1,018.95 and 487.30
Similar ratio
Find fourth proportional to 1,018.35, 1,526.18 and 729.45
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.