The Smart Scholars Method

Consider p = 3*n*(n – 2)/2.

For p to be an integer, n has to be even. If n = 6, p = 36 which is lower than 50.

For lower values of n, p is even lower.

If n = 10, p 120 >which is higher than 100.

For higher values of n, p is even higher.

For p to be between 50 and 100, n has to be 8.

Then p = 3*8*6/2 = 72.

Sanity Check:

Bikaner Bhujiawala is ready to supply 8 plates per Rs 1000.

Bengali Mishtanna Bhandaar would give only 6 plates.

As 72 plates are ordered, Brinda would have to pay 72*(1000/8) = Rs 9,000 to Bikaner Bhujiawala.

If the order went to Bengali Mishtanna Bhandaar, she would have to pay 72*[1000/6)] = Rs 12,000.

Thus she has saved Rs 12,000 – Rs 9,000 = Rs 3,000.

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