Question

One of four main blood types can be found in a human body. They are known as A, B, AB and O. Each blood type can be further classified as either a Rhesus positive (+) or Rhesus negative (–). For example, a possible combination is blood type O and Rhesus negative which is written as O–. The data below shows the distribution of the blood types and Rhesus types of given blood type for a Blood Donation Center recorded (in percentages) for the year 2023. Blood Group Rhesus factor Number of person (in %) O O− x O+ 30 A A− 8 A+ 24 B B− 6 B+ 18 AB AB− 1 AB+ 3

1.  Find the value of x.   (1)
2. Find the probability that a randomly selected person has a Rhesus negative blood type.   (1)
3. 1. What is the probability that the person selected from the record is Rhesus positive but neither blood type A nor B?   (2)
      OR
   2. People with blood type AB positive (AB⁺) are known as the universal recipient and with blood type O negative (O^–) are known as universal donor. Find the probability of a selected person to be neither universal recipient nor universal donor.

Answer 1

i. x = 100 – (30 – 32 – 24 – 4)

= 100 − 90

= 10

ii. P(selected person to have Rhesus negative blood type) 

= `(10 + 8 + 6 + 1)/100`

= `25/100` or `1/4`

iii. (A) P(person is Rhesus positive but neither A nor B type blood)

= `(30 + 3)/100`

= `33/100`

OR

iii. (B) P(person is neither universal recipient nor universal donor)

= `1 - ((3 + 10))/100`

= `1 - 13/100`

= `87/100`