New Scientist - USA (2020-08-01)

#70 Taking the biscuit

Alpha and Betty play a rather

greedy game. There are eight

digestive biscuits in one jar, and

four rich tea biscuits in another.

Each player can collect biscuits

in one of two ways. They either:

• Take any number of biscuits
  from one jar, or


• Take an equal number of biscuits
  from both jars.

The player who takes the last

biscuit wins the game and gets

to keep all the biscuits.

Alpha is set to go first.

What biscuit or biscuits

should she take?

Answer next week

#69 Cutting the flag

Solution

Three-fifths of the trapezium

is blue, the same proportion

as for the uncut flag.

One way to see this is to make a

copy of the trapezium, rotate it by

180 degrees and place it next to

the first. It will form a parallelogram

made of five stripes, now all of

equal length. Three-fifths of the

parallelogram is blue, and because

the two trapezia were identical,

they will also have the same

fraction of blue.

54 | New Scientist | 1 August 2020

Puzzle

set by Zoe Mensch

Quick

quiz #62

Answers

1 Testosterone

2 Continental drift,

or what is now plate

tectonics; Wegener

first suggested that

Earth’s continents

were moving relative

to one another in

1912

3 Cabbage white

butterfly; for those

that distinguish,

P. rapae is the small

white, P. brassicae

the large white

4 Vera Rubin. Her

studies of rotating

galaxies suggested

unseen “dark” matter

must far outweigh

normal matter

within them

5 Alveoli

Twisteddoodles

for New Scientist

Tom Gauld

for New Scientist

The back pages