Hi
gullyboy09 let me try to help
Given
The average bill is $48 per customer. The tip rate for any individual is either 15% or 20%.
Let B be the Total Bill, T be the Total Tip, and N be the Number of Customers.
We know B / N = 48, which means
B= 48N.
The question asks: Is T / N > 8?
Since N=B/48
Then is T/B/48>8 T/B>1/6
Is the total tip pool strictly greater than 16.67% of the total bill pool?
Lets check Statement 1
Most of yesterday’s customers chose to leave a 20% tip
Let's test this with 3 customers whose average bill is $48 (Total Bill = $144)
Case A (Large bills and small tips)
Customer 1 (Bill: $140) leaves 15% tip = $21.00
Customer 2 (Bill: $2) leaves 20% tip = $0.40
Customer 3 (Bill: $2) leaves 20% tip = $0.40
Most (2 out of 3) left a 20% tip.
Total Tip = $21.80.
Average Tip = $21.80 / 3 = $7.27 Is it > $8? NO
Case B (Large bills n left large tips)
Customer 1 (Bill: $2) leaves 15% tip = $0.30
Customer 2 (Bill: $71) leaves 20% tip = $14.20
Customer 3 (Bill: $71) leaves 20% tip = $14.20
Most left a 20% tip. * Total Tip = $28.70. Average Tip = $28.70 / 3 = $9.56
Is it > $8? YES
Because we get both a YES and a NO, Statement (1) is INSUFFICIENT.
gullyboy09
Hi
kevincan, can you please explain how to approach Statement 1 mathematically? I tried one example, and example I took was satisfying the condition, now looking at the example you have given, I can see we cannot be sure with Statement 1. So it would be good if we try to solve mathematically, will you be able to help? Thanks in advance
