There are three cards in a bag. One is red on both sides, one is blue on both sides, and one is red on one side but blue on the other side. A card is drawn at random and placed on a table, with the blue side facing up. What is the probability that the hidden side is also blue?
In a perfectly functional quad-rotor, what is its maximum upward acceleration? These are two of 14 questions plastered on the backs of seats on the upper deck of a bus plying the service 96 route, which loops around the National University of Singapore (NUS) from Clementi Bus Interchange.
Designed for tertiary-level students, the questions were crafted by 14 scientists and engineers from Singapore's defence research and development organisation, DSO National Laboratories.
Accompanying each question is a short profile of the scientist or engineer responsible for it.
Titled #ChallengeInTransit, the questions cover topics such as physics, chemistry and cyber security.The aim of the challenge is to raise awareness about science and engineering, said DSO, and, at the same time, transform a bus ride into a more engaging journey, said Tower Transit Singapore, which provided the bus.
The response has been very encouraging, Ms Serene Tan, DSO's human resource and communications director, told a media briefing yesterday. In just over a week since the challenge started on Jan 15, nearly 100 answers have been submitted online by commuters, mostly university students and some working adults.
Some answers included step-by-step workings, showing the commuters' thought process, said Mr Kenny Wong, head of corporate communications at DSO.
Some questions might be tough, but students here are quite smart and I think they would have fun with it if they give it a go.
MS ALISA LOH HUI TING, a real estate agent who gave the challenge a go.
Real estate agent Alisa Loh Hui Ting, 28, was among those who took up the challenge, which requires commuters to tackle only one question.
She took on Question 11 on probability which related to the red and blue cards. This question was popular among those who responded, along with another on unmanned aerial vehicles.
Ms Loh described the move to challenge commuters as innovative, saying it encouraged them to think as opposed to listening to music or staring out of the bus window.
"Some questions might be tough, but students here are quite smart and I think they would have fun with it if they give it a go," she said.
Commuters can submit their answer to curiousbus.sg
At the end of January, February and March, all correct answers will be collated and one winner will be drawn from each month to receive a portable drone worth more than $100 from tech company Hubsan.
Hints and announcements will be shared on DSO's Facebook and Instagram accounts, @dso.sg and @discoverdso respectively. All solutions will be revealed after the contest ends on March 30.