Home / 865.88-1,299-378.80

Finding the Fourth Proportional to 865.88, 1,299 and 378.80

Calculator

Solution

The fourth proportional to 865.88, 1,299 and 378.80 is: 568.28

Step by Step Solution

  1. Step 1: Write the proportion equation
    865.88 : 1,299 = 378.80 : x
  2. Step 2: Convert to fraction form
    865.88/1,299 = 378.80/x
  3. Step 3: Cross multiply
    865.88x = 1,299 × 378.80
  4. Step 4: Simplify right side
    865.88x = 492,061.20
  5. Step 5: Solve for x
    x = 492,061.20/865.88
  6. Step 6: Final answer
    x = 568.28

Related Problems

Find fourth proportional to 432.94, 649.50 and 189.40
Half scale
Find fourth proportional to 1,731.76, 2,598 and 757.60
Double scale
Find fourth proportional to 866.88, 1,300.50 and 379.80
Similar ratio
Find fourth proportional to 1,298.82, 1,948.50 and 568.20
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.