Question 4:
Solution:
Probability of picking a Singapore stamp=1−15−815=415Given that John has 20 Singapore stamps,∴
John has a collection of stamps from Thailand, Indonesia and Singapore. He picks one stamp at random. The probability of picking a Thailand stamp is
15
and the probability of picking an Indonesia stamp is
815.
John has 20 Singapore stamps. Calculate the total number of stamps in his collection.
Solution:
Probability of picking a Singapore stamp=1−15−815=415Given that John has 20 Singapore stamps,∴
Question 5:
A box contains 36 green erasers and a number of red erasers.
If an eraser is picked randomly from the box, the probability of picking a red eraser is . Find the number of red erasers.
Solution:
Probability of picking a green eraser = 1 – =
Total number of erasers in the box = 36 × = 96
Hence, number of red erasers in the box = 96 – 36 = 60
A box contains 36 green erasers and a number of red erasers.
If an eraser is picked randomly from the box, the probability of picking a red eraser is . Find the number of red erasers.
Solution:
Probability of picking a green eraser = 1 – =
Total number of erasers in the box = 36 × = 96
Hence, number of red erasers in the box = 96 – 36 = 60