Question

Each of the integers 1-25 is written on an individual card and placed in a hat. You

randomly draw a card. How many favorable outcomes are there for choosing a card
with an odd number?
Ο Α. 2
OB. 11
O C. 13
OD. 25

Answer 1

Explanation:

Comment

If you know this formula

tn = t1 + (n - 1)*d then you don't even have to count how many odd numbers there are. If you don't know the formula, then you have to count how many odds there are between 1 and 25 inclusive. Just to save you the trouble, there are 13.

Givens

1 = t1

25 = tn

d = 2

Solution

25 = 1 + (n - 1)*2 Subtract 1 from both sides?

25-1 = 1-1 + (n - 1)*2 Combine

24 = (n - 1) * 2 Divide by 2

24/2 = (n - 1)*2/2

12 = n - 1 Add 1 to both sides

12 + 1 = n - 1 + 1 Combine

13 = n

Answer

So you have 13 cards that will bring success.