ERJ Brainteaser: April
29 Mar 2020
At last it seemed we had a single clear winner for our top award. That was until Q4 made it a neck-and-neck race at the finishing line. Big congratulations to John Bowen and Andrew Knox, joint holders of the April Brainiac of the Month title.
Complete the series: Tokyo, London, Helsinki, _, Berlin.
Clues: 2020, 1944, 1940, ...., 1916
Answer: Tokyo (1940) was missing from this list of city locations for postponed or cancelled Olympic games. Easy enough with the years added as clues during the week, so a special mention to Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands, for spotting this on Monday. Also on the podium were: David Mann, key account manager, SPC Rubber Compounding, UK; John Bowen, consultant, Bromsgrove, UK; Stephan Paischer, head of product management special products, Semperit AG Holding, Vienna, Austria; Well done to all and everyone else who had a go.
Bonus question:
Using any combination of addition, subtraction, multiplication, division, see how close to 952 you can get using some or all of the following numbers:
3, 5, 25, 50, 75, 100. (The result has to be an integer, and the above numbers can only be used once in your calculation)
The closest anyone got was 953, as worked out by Andrew Knox, John Bowen and (as shown here) David Mann:
100/5 = 20
20 x 50 = 1000
1000 - 75 + 25 + 3 = 953
There are two taps on a reactor. One releases hot water, the other cold water, into the vessel, but at varying pressures. If the hot water is 105°F and the cold water is 45°F, and operators can rotate the tap at most 360 degrees, how much would they have to rotate the cold water tap to get the temperature to be 98.6°F, if the hot water is turned on all the way, and could not be turned down?
Answer: This did prove a tricky teaser, with lots of replies in but only three with the correct answer, 43°. Very well done to John Bowen, consultant, Bromsgrove, UK: Michele Girardi, Scame Mastaf Spa, Suisio, Italy; Stephan Paischer, head of product management special products, Semperit AG Holding, Vienna, Austria; and everyone one else who had a go.
Some neat workings out, none more so than Michele Girardi’s:
Setting up an enthalpy balance taking 98.6 as reference temperature, hot flow = 1 and cold flow = x, we have:
1*(105-98.6)+x*(45-98.6) = (1+x)*(98.6-98-6) =0
x=-(105-98.6)/(45.98.6) = 0.1194
Supposing the flow is proportional to angle angle of cold tap = 0.1194*360 = 43°
Bonus question:
Using any combination of addition, subtraction, multiplication, division, see how close to 940 you can get using some or all of the following numbers:
1, 2, 25, 50, 75, 100.
Well done again to John Bowen and to Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands; the only Brainiacs to hit the target number spot on:
50 x 25 = 1250
1250 + 2 = 1252
50 + 25 = 75
1252 x 75 = 93900
93900/100 = 939
939 + 1 = 940
To manage access to the control system of his brewery, Pete has set a tricky pass-code, comprising a 3-digit number, a 4-digit number and another 3-digit number. As a reminder, he has jotted down each number with a mathematical clue (on the left) but forgotten to include the last one. Help Pete work out the final code number X, so he can get things going.
Clue A: 7, 13, 14 = 637; Clue B: 11, 14, 26 = 2,002; Clue C: 8, 9, 21 = X.
Answer: A fairly straightforward case of identifying that the first two codes can be generated by multiplying the numbers in each clue together and then dividing by two – so that the answer is 756. Cheers to: John Bowen, consultant, Bromsgrove, UK: David Mann, key account manager, SPC Rubber Compounding, UK; France Veillette, chef environnement, Usine de Joliette, Bridgestone Canada Inc., Canada: Michael Easton, sales and marketing director, Globus Group, Manchester, UK; Jose Padron, material development specialist, Waterville TG Inc., Waterville, Québec, Canada; Salah, Younis, retiree, previously an industrial and operations engineer with Hyundai, Lebanon; Hans-Bernd Lüchtefeld, marketing manager – automotive safety, Indorama Mobility Group, PHP Fibers GmbH (see answer below); Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands; Paul Knutson, textile engineer, Timken Belts, Springfield, Missouri, USA; Latif, Erdogan, retired and working as a private industry consultant, after many years working in R&D at Continental, Hanover, Germany.
Which number completes this series?
18032, 1832, 212, 50, _ .
Answer: Not easy and not for the first time, there was more than one way of looking at our teaser. Once you had recognised that this was about converting Fahrenheit to Celcius – 212 was a clue for some – you could work the series out as: 10,000, 1,000, 100, 10, 1: making the answer 33.8(F). Alternatively, the series could be 10,000, 1,000, 100, 10, 0 to get to freezing point 32(F).
Extremely well done, so, to: Katharina Gottfried, Arlanxeo Deutschland GmbH, Köln, Germany. John Bowen, consultant, Bromsgrove, UK: David Mann, key account manager, SPC Rubber Compounding, UK; France Veillette, chef environnement, Usine de Joliette, Bridgestone Canada Inc., Canada: Michael Easton, sales and marketing director, Globus Group, Manchester, UK; Andrew Knox, Rubbond International, Ohé en Laak, The Netherlands; Paul Knutson, textile engineer, Timken Belts, Springfield, Missouri, USA; Michele Girardi, Scame Mastaf Spa, Suisio, Italy; Jose Padron, material development specialist, Waterville TG Inc., Waterville, Québec, Canada; Hans-Bernd Lüchtefeld, marketing manager, Indorama Mobility Group, PHP Fibers GmbH, Obernburg, Germany; Stephan Paischer, head of product management special products, Semperit AG Holding, Vienna, Austria.
A picture tells a thousand words, so we let Hans-Bernd Lüchtefeld (image above) Jose Padron (below) show how it all works out:
