#65 Father figures
Jasmine has discovered that she has a special relationship with her dad. A few times, she has noticed that his age has been the reverse of hers: this year, she was 47 and her dad was 74. But this also happened when she was 36 and he was 63. It first happened when she was 14 and he was 41.
Jasmine thinks this might be unusual, so she checks out if it has happened to any of her 90 Facebook friends. How many of them do you think will discover this age reversal has happened with their own dad at some point?
Answer next week
#64 Ruritanian carpet
Answers
Call the radius of the room R, and the radius of the central pillar r. The area of the carpet is:
蟺搁2 鈥� 蟺r2 = 蟺(R2 鈥� r2).
But from Pythagoras we know 52 + r2 = R2, and so R2 鈥� r2 = 25
So the area of the carpet is 25蟺, or roughly 78.5 square metres.
Quick quiz #57
1 Which African country is named after an 11th century city, the ruins of which lie south of Masvingo?
2 Pioneering US agricultural scientist George Washington Carver famously worked with which soil-improving legume crop, Arachis hypogaea?
3 Who calculated the orbital trajectories that first got NASA astronauts safely into space and died earlier this year aged 101?
4 Homo habilis, Paranthropus boisei, Homo erectus and our own Homo sapiens form the procession of hominin species through which Tanzanian landscape?
5 The astrophysicist and science populariser Neil deGrasse Tyson is director of which planetarium near Central Park in New York City?
Answers
1 Zimbabwe. The site is now known as Great Zimbabwe
2 The peanut or groundnut
4 The Olduvai Gorge, one of the most famous of all palaeoanthropological sites
5 The Hayden Planetarium at the Rose Center for Earth and Space