There is one knot in a string.
When I divide this string into 5 equal parts, knot was in the 2nd section from the left.
When I divide the same string into 8 equal parts, knot was in the 4th section from the left.
When I divide this string into 30 equal parts, in which section is knot?
There isn't a knot in the end of the string divided at any division.
Answer
12th
Solution
The length of the string is set to 120 cm which is the least common multiple of 5, 8 and 30.
Answer
12th
Solution
The length of the string is set to 120 cm which is the least common multiple of 5, 8 and 30.
When I divide it into 5 equal parts, knot was in the 2nd section from the left.
According to the calculation of 120/5 = 24, 24 × 1 = 24 and 24 × 2 = 48, knot was in the section of less than 48 cm and beyond 24 cm from the left.
When I divide it into 8 equal parts, knot was in the 4th section from the left.
According to the calculation of 120/8 = 15, 15 × 3 = 45, and 15 × 4 = 60, knot was in the section of less than 60 cm and beyond 45 cm from the left.
Accordingly, it is found that knot is in the section of less than 48 cm beyond 45 cm from the left.
According to 120/30 = 4, 4 × 11 = 44 and 4 × 12 = 48，when I divide it into 30 equal parts, knot is in the 12th section.
