Question

Suppose that everyone in the class has hand sanitizer. Suppose that Shafiq uses hand sanitizer and it only kills 25% of the bacteria on his hand. I shake his hand and a day later, mine still works 100% and Shafiq’s works 0%. The next day I shake Melissa’s hand, whose hand sanitizer works only 50%. A day later both of our sanitizers are at 0%. Explain what happened in Shafiq’s case, Mr. Ashraf’s case, and Melissa’s case.

Answer 1

Shafiq's sanitizer only killed 25% of bacteria, Melissa's sanitizer killed 50%, and Mr. Ashraf's sanitizer worked 0% after shaking Shafiq's hand.

Step-by-step explanation:

In Shafiq's case, his hand sanitizer only kills 25% of the bacteria on his hand, so there were still bacteria left on his hands after he used the sanitizer. When you shook his hand, some of those bacteria transferred to your hand. Since your hand sanitizer works 100%, it was able to kill all the bacteria that were transferred from Shafiq's hand.

In Melissa's case, her hand sanitizer works 50%, so it killed some but not all of the bacteria on her hand. When you shook her hand, some of the remaining bacteria transferred to your hand. Since your sanitizer also works 100%, it was able to kill all the bacteria that were transferred from Melissa's hand.

In Mr. Ashraf's case, it is unclear why his hand sanitizer worked 0% after shaking Shafiq's hand. There could be several reasons for this, such as a defective hand sanitizer or improper use, but it is difficult to determine without more information.