Home / 786.05-1,085.21-491.72

Finding the Fourth Proportional to 786.05, 1,085.21 and 491.72

Calculator

Solution

The fourth proportional to 786.05, 1,085.21 and 491.72 is: 678.86

Step by Step Solution

  1. Step 1: Write the proportion equation
    786.05 : 1,085.21 = 491.72 : x
  2. Step 2: Convert to fraction form
    786.05/1,085.21 = 491.72/x
  3. Step 3: Cross multiply
    786.05x = 1,085.21 × 491.72
  4. Step 4: Simplify right side
    786.05x = 533,611.58
  5. Step 5: Solve for x
    x = 533,611.58/786.05
  6. Step 6: Final answer
    x = 678.86

Related Problems

Find fourth proportional to 393.02, 542.60 and 245.86
Half scale
Find fourth proportional to 1,572.09, 2,170.41 and 983.43
Double scale
Find fourth proportional to 787.05, 1,086.59 and 492.72
Similar ratio
Find fourth proportional to 1,179.07, 1,627.81 and 737.57
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.