Directions for question :
About eighty metres inside from Gate No 4 of the Jadavpur University Campus was the iconic ‘Milan Da’s Canteen’, the oldest out of the eight canteens in the campus, catering to students, researchers, faculties, staff and even ex-students of the university for decades since the 60’s, especially for the engineering and art departments. Milan Da, the owner, was quite an innovative chef, and churned out tasty, innovative delicacies with equally innovative names, so popular and iconic, that even NRI ex-students on a visit to Kolkata would line up to savour them.
Milan Da’s wife, the ‘Boudi’ (sister-in-law in Bengali) to all – young or old, student or faculty – handled the cash and had a memory and calculation prowess which was extraordinary. She could exactly remember who ordered what at what time of the day and how much dues were carried forward for each customer.
One month of a particular year she decided to check out which of the snack items of the canteen were being preferred more, and hence started to keep a note of what all the customers – students, faculties and staff of the engineering and arts department – were ordering during snack times. After one month of continuous watch, she come to the following conclusions :
a) Three of the snack items were the clear best-sellers :
b) The number of customers preferring all the three snack items was the same as that preferring none of the three
c) The number of residents preferring any two of the three was the same as those preferring any other two, which in turn was the same as those preferring none of the three
d) The number of customers preferring only the ‘Dhoper Chop’ was the same as those preferring only the ‘Ghorar Dim’, and each were twice the number of customers preferring only the ‘Bom’
e) Half the number of customers who preferred the ‘Bom’ preferred at least one of either the ‘Dhoper Chop’ or the ‘Ghorar Dim’.
Question :
If 105 customers did not prefer any one of the three snack items, then what was the total number of customers at Milan-Da’s Canteen ?
2100
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We know that the Venn diagram representing the distribution of preferences at Milan-Da’s Canteen is :
If 105 customers did not prefer any one of the three snack items, it implies that
5% of the customers = 105 customers
or, 100% of the customers = (105*100)/5 = 2100 customers
Hence, if 105 customers did not prefer any one of the three snack items, then the total number of customers at Milan-Da’s Canteen = 2100