Jenny goes hiking every 15 days and swimming every 6 days. She did both kinds of exercise today. How many days from now will she go both hiking and swimming again if today is January 8th
A way to solve this, is to find a link between number 15 and 6
List the multiples of 15: (15,30,45,60...)
List the multiples of 6: (6,12,18,24,30...)
Notice 30 in both
Well if she goes swimming every 6 days and hiking every 15 days
Swimming every 6 days so after 30 days she will go swimming with hiking as she go hiking each 15 days, the next 15 days which will be january 23th she will go only hiking since she will go swimming on 14th jan. and 20 jan, 26 jan. 1 feb. , 7th feb.
they don't meet there but notice the next swimming will be january 23th + 15 days = 7th feb
so on 7th february she will go both swimming and hiking
(Notice it took a while , a faster way would be notice the multiplies between 6 and 15, in 15 to reach 30 we took 30 days, in 6 to reach 30 we took 30 days as well) so we just need to add 30 days + Current date which is january 8th (Assuming january ends at 31th) it will be february 7th!