VJesus12 wrote:A collection of 36 cards consists of 4 sets of 9 cards in each set are numbered 1 through 9. If one card has been removed from the collection, what is the number on that card?
(1) The units digit of the sum of the numbers on the remaining 35 cards is 6.
(2) The sum of the numbers on the remaining 35 cards is 176.
Target question: What is the number on the card?
Given: A collection of 36 cards consists of 4 sets of 9 cards in each set are numbered 1 through 9.
Statement 1: The units digit of the sum of the numbers on the remaining 35 cards is 6.
1+2+3+4+5+6+7+8+9=45
Since there are 4 sets of cards numbered 1 to 9, the SUM of all 36 cards = 4(45) =
180
When we remove one card, the sum of the REMAINING 35 cards = --6 (units digit 6)
In other words,
180 - (value of chosen card) = --6
So,
the value of the chosen card must be 4
Since we can answer the
target question with certainty, statement 1 is SUFFICIENT
Statement 2: The sum of the numbers on the remaining 35 cards is 176.
In other words,
180 - (value of chosen card) = 176
So,
the value of the chosen card must be 4
Since we can answer the
target question with certainty, statement 2 is SUFFICIENT
Answer: D
Cheers,
Brent
