#19 The vicar鈥檚 age
A bishop visited his friend the vicar on her birthday. Knowing the bishop liked number puzzles, the vicar told him about a family that had just joined her church.
鈥淚f you multiply their three ages together, you get 2450, and if you add their ages together, you get your own age, your grace.鈥�
The bishop, after some thought, said: 鈥淚 can鈥檛 be certain how old everyone in the family is.鈥�
The vicar responded: 鈥淚 am older than everyone in that family.鈥�
The bishop could then tell how old everyone was.
How old was the vicar on that day?
Answer next week
#18 Cable on the moon
Solution
A power cable buried in a 1-metre deep trench encircling the moon鈥檚 equator will only be about 6 metres shorter than if it was laid on the surface.
The radius of the moon (R) at the equator is , but you don鈥檛 actually need that figure to answer this question.
The length of cable on the surface is given by the formula 2蟺R.
Burying the cable 1 metre down reduces the radius to R-1. The new cable length is therefore given by 2蟺(R-1), which expands to give 2蟺R-2蟺. Subtracting this from the cable length on the surface gives a difference of 2蟺 metres.
So the buried cable is a mere 6.3 metres shorter than one on the surface.
Quick quiz #18
1 Nihonium, Tennessine, Oganesson 鈥� what fourth name is missing from this list?
2 9,192,631,770 what of what equals what?
3 The ICZN, based in Singapore, and the IAPT, based in Bratislava, Slovakia, do what?
4 A golfball-sized lump of 90 per cent platinum and 10 per cent iridium (by mass) fulfilled what function until 2019?
5 FlyBase collates genetic information concerning which fast-breeding organism beloved of biologists?
Answers below
Quick quiz #18
Answers
1. Moskovium. They are elements added to the periodic table by the International Union of Pure and Applied Chemistry in 2016.
2 The International Bureau of Weights and Measures (BIPM) says 9,192,631,770 oscillations of the hyperfine ground states of the caesium-133 atom = 1 second.
3 The International Commission on Zoological Nomenclature and the International Association for Plant Taxonomy ensure consistent animal and plant names.
4 It was the international prototype kilogram, until the BIPM replaced it with a standard based on the Planck constant.
5 The fruit fly Drosophila melanogaster
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