Why did they had "Monetary Pang of Guilt"?

Algebra Level 3

Three friends while returning from a movie stopped to eat at a restaurant. After dinner, they paid their bill and noticed a bowl of mints at the front counter. Sita took 1/3 of the mints but returned four because of monetary pang of guilt. Fatima then took 1/4 of what was left behind but returned three for similar reasons. Eswari then took half the remainder but threw two back into the bowl. The bowl had only 17 mints left after their raid was over. How many mints were originally in the bowl?

31 48 41 56 46 38

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3 solutions

Chew-Seong Cheong
Apr 28, 2017

Let the original number of mints be n n . Then, the number of mints left after:

  • Sita took and returned, n s = n 1 3 n + 4 = 2 3 n + 4 n_s = n - \frac 13 n + 4 = \frac 23 n + 4
  • Fatima took and returned, n f = n s 1 4 n s + 3 = 3 4 n s + 3 n_f = n_s - \frac 14 n_s + 3 = \frac 34 n_s + 3
  • Eswari took and returned, n e = n f 1 2 n f + 3 = 1 2 n f + 2 n_e = n_f - \frac 12 n_f + 3 = \frac 12 n_f + 2

And after Eswari took and returned there were 17 mints remaining. Therefore, we have:

n e = 17 1 2 n f + 2 = 17 n f = 30 3 4 n s + 3 = 30 n s = 36 2 3 n + 4 = 36 n = 48 \begin{aligned} n_e & = 17 \\ \frac 12 n_f + 2 & = 17 \\ \implies n_f & = 30 \\ \frac 34 n_s + 3 & = 30 \\ \implies n_s & = 36 \\ \frac 23 n + 4 & = 36 \\ \implies n & = \boxed{48} \end{aligned}

Thanks for a clear solution

Saraswat Bhattacharya - 4 years, 1 month ago

Let us assume that the total number of mints present in the bowl be x . No. of mints taken by Sita (in terms ofx) =1/3 x-4 =x/3-4 =(x-12)/3 Balance of mints in the bowl after the first raid from Sita =x-((x-12)/3) =(3x-(x-12))/3 =(2x+12)/3 No. of mints taken by Fatima (in terms ofx) =1/4 [(2x+12)/3]-3 =1/4×(2(x+6))/3-3 =(x+6)/6-3 =((x+6)-18)/6 =(x-12)/6 Balance of mints in the bowl after the second raid from Fatima =[(2x+12)/3]-[(x-12)/6]
=(4x+24-x+12)/6
=(3x+36)/6 =(3(x+12))/(3(2))
=(x+12)/2
No. of mints taken by Eshwari (in terms ofx) =1/2 [(x+12)/2]-2 =(x+12)/4-2 =(x+4)/4 Balance of mints in the bowl after the last raid from Eshwari =(x+12)/2-(x+4)/4 =(2x+24-x-4)/4 =(x+20)/4 According to the question, 17 mints were left in the bowl after the raid was over. ∴(x+20)/4=17 x+20=68 x=48


too lengthy

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tor ma ke chudbo

Saraswat Bhattacharya - 3 years, 8 months ago

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etake abar ke upvote koreche

A Former Brilliant Member - 3 years, 8 months ago
Saya Suka
Apr 13, 2021

The initial number of mints must be a multiple of 3, so 48 is the only possible answer from all the options given.

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