A plant uses the same group of workers for a 4 day production run.
Each worker works one shift per day, either the morning shift or the evening shift, and each worker produces the same number of units in any shift worked.
On Day 1, all workers work the morning shift. Once a worker is assigned to the evening shift, that worker remains on the evening shift for the rest of the production run.
On Day 2, one third of the workers who worked the morning shift on Day 1 are assigned to the evening shift.
On Day 3, one third of the workers who worked the morning shift on Day 2 are assigned to the evening shift.
On Day 4, one third of the workers who worked the morning shift on Day 3 are assigned to the evening shift.
Let the number of workers on Day 1 (all morning shifts) be x and number of units produced per shift be y.
Day 1: Workers = morning shifts = x; Unit produced = xy; Units produced in evening shift = 0
Day 2: Workers = x; Morning shifts = 2x/3; Evening shifts = x/3; Units produced = xy; Units produced in evening shift = xy/3
Day 3: Workers = x; Morning shifts = (2/3)(2x/3) = 4x/9; Evening shifts = 5x/9; Units produced = xy; Units produced in evening shift = 5xy/9
Day 4: Workers = x; Morning shifts = (2/3)(4x/9) = 8x/27; Evening shifts = 19x/27; Units produced = xy; Units produced in evening shift = 19xy/27
Total number of units produced by the evening shift over the four days (E) = 0 + xy/3 + 5xy/9 + 19xy/27 = (9+15+19)xy/27 = 43xy/27
Total number of units produced by both shifts over the four days (B) = 4xy
E/B = (43xy/27)/(4xy) = 43/108 = 86/216
| Evening shift | Both shifts |
| 86 | 216 |