Probability and Tree Diagrams

A lego storage box is left with 4 blue and 7 red bricks. Yonel takes a brick from the box at random and attaches it to his new castle. He then chooses another brick from the same box at random.

Fill in the tree diagram.

P(1st brick is red) : A = ​ (a)  

P(2nd brick is blue | 1st brick is blue): B = ​ (b)  

P(2nd brick is red | 1st brick is blue): C = ​ (c)  

P(2nd brick is blue | 1st brick is red): D = ​ (d)  

P(2nd brick is red | 1st brick is red): E =​ (e)  

• 7/11

• 3/10

• 7/10

• 6/10

• 8/11

• 4/10

• 4/11

• 6/11

A lego storage box is left with 4 blue and 7 red bricks. Freddy takes a brick from the box at random and attaches it to his new castle. He then chooses another brick from the same box at random.

What is the probability that both bricks are the same color?

(a)  

• 1/8
• 1/2
• 1/24
• 1/16

• 1/48
• 1/6
• 1/8
• 1/24

What is the probability of the arrow stopping on “X” on the first spin and “F” on the second spin?

• 5/6

• 1/36

• 1/3

• 1/6

Q1. How many legs does a spider have?

• 6

• 12

• 2

• 10

• 1/4
• 1/8
• 1/2
• 1/6

• 1/2
• 1/8
• 1/3
• 1/12

A fruit basket contains
9 apples, 3 bananas, 7 oranges, 5 pears, and 1 grapefruit. Kyle randomly chooses a fruit, does not replace it, then chooses another. What is the probably that he chose two pears? 

• 9/49

• 4/125

• 1/10

• 1/30

In a box there are 3 red pens, 2 green pens, and 1 blue pen. What is the probability of picking a red pen, replacing it, and then picking a green pen?

• 1/2

• 4/11

• 1/6

• 2/3