Three letters are randomly drawn from the word TUESDAY. How

Question

Three letters are randomly drawn from the word TUESDAY. How many possible selections are there?

maratikus · Answer

7C3 = 35 sets of 3 letters

bmwhype2 · Answer

why is it comb if we are drawing three letters? shouldnt it be perm

maratikus · Answer

because the order of letters doesn't matter

bmwhype2 · Answer

then how is thie one below a perm question

Given ABCDE, how many ways can we draw two letters out?

maratikus · Answer

that's a different story - here the order is important because the process of drawing letters has a certain order and we are counting sets of ordered letters because they define a drawing process . Therefore, 5 ways of choosing the first letter, 4 ways of choosing the second letter -> 20

If the problem was to calculated the number of ways 3 letters can be drawn from the word TUESDAY - the answer would be 7*6*5. However, the question implies that we are asked the number of sets (or selection) of three letters. Hope that helps.

bmwhype2 · Answer

thanks. got tripped up on the terminology

selection / sets = combinations
draw w/o replacement = perm

GMAT TIGER · Answer

rememer for arrangement and group (selection). the former is permutation where as the later one is combination.

permutation => abc and acb are two diff. 
combination => abc and acb are same.

GMATBLACKBELT · Answer

b/c TUESDAY ---> TUE is the same as UTE. thus its 7!/3!4! =35

Three letters are randomly drawn from the word TUESDAY. How

Prep Toolkit

Top 5 GMAT Debrief Videos

615 to 715 in 15 Days (Ria's Strategies)

More than Quant/Verbal Abilities: Speed vs. Accuracy

745 with Only Self-Prep and GMAT Club

From 555 to 765: 210-point Improvement

Perfect 805 Score Debrief by Julia

My Rewards