Skip to main content

Two sticks and matchbox, measure exactly 45 minutes by burning these sticks


Question: You have two sticks and matchbox. Each stick takes exactly an hour to burn from one end to the other. The sticks are not identical and do not burn at a constant rate. As a result, two equal lengths of the stick would not necessarily burn in the same amount of time.  How would you measure exactly 45 minutes by burning these sticks?

Answer: This puzzle used to be asked in Wall Street interviews long time ago. It is very rare for this question to be asked now but it is a very good question to help you think a little outside the normal thought process.

The answer is really simple. Since the sticks do not burn at a constant rate, we can not use the length of the stick as any sort of measurement of time. If we light a stick, it takes 60 minutes to burn completely. What if we light the stick from both sides? It will take exactly half the original time, i.e. 30 minutes to burn completely.

0 minutes – Light stick 1 on both sides and stick 2 on one side.
30 minutes – Stick 1 will be burnt out. Light the other end of stick 2.
45 minutes – Stick 2 will be burnt out.

If you have any interesting questions, feel free to email them to support@goforexam.in
Labels:

Comments

Post a Comment

Your Comment Here!.....

Popular posts from this blog

CIVIL SERVICES' (I.A.S.) EXAMINATION

The Union Public Service Commission (U.P.S.C.)  conducts Civil Services' Examination once a year in two stages. The Preliminary Examination (Objective Type) for selection of candidates for the Main Examination is held in the month of May. The Civil Services Main Examination  is held in the months of October/November. Blank application forms and other particulars are published in the Employment News, generally in the month of December. The last date for the submission of applications to the Secretary, Union Public Service Commission, Dholpur House, Shahjahan Road, NewDelhi-11001 1 is usually the last week of January of the year of examination. The Combined Civil Services Examination is conducted for Recruitment to the following Services/Posts: 1. Indian Administrative Service. 2. Indian Foreign Service. 3. Indian Police Service. 4. Indian P & T Accounts & Finance Service, Group 'A'. 5. Indian Audit and Accounts Service, Group 'A'. 6. Indian Customs and Centr
1 comment
Read more

AGRICULTURAL SCIENTIST RECRUITMENT BOARD

Agricultural Research Service National   Eligibility  Test/ Senior Research Fellowship Examination  The Agricultural Scientists Recruitment Board (ASRB)  holds a Competitive Examination for recruiting Scientists of the ARS in the pay scale of Rs. 8,000-13,500 in the ICAR Institutes, combined with National Eligibility Test (NET) for recruitment of Lecturers and Assistant Professors by the State Agricultural Universities (SAUS) and for award of ICAR Senior Research Fellowships. The selected candidates for Agricultural Research Service must serve in the institutes to which they are posted until they find appointment for higher positions through selection at other institutes. (i) Candidates successful in ARS are appointed as Scientists in the Indian Council of Agricultural Research in the pay scale of Rs. 8,000-13,500. (ii) Candidates clearing the National Eligibility Test are recommended to various State Agricultural Universities who will consider them for appointment as Lecturers or A
Post a Comment
Read more

Predict the output or error(s) for the following:

1 . void main(){ int const * p=5; printf("%d",++(*p)); } Answer: Compiler error: Cannot modify a constant value. Explanation: p is a pointer to a "constant integer". But we tried tochange the value of the "constant integer". 2. main() {  char s[ ]="man"; int i;  for(i=0;s[ i ];i++) printf("\n%c%c%c%c",s[i],*(s+i),*(i+s),i[s]); } Answer: mmmm aaaa nnnn Explanation: s[i], *(i+s), *(s+i), i[s] are all different ways of expressing the same idea. Generally array name is the base address for that array. Here s is the base address. i is the index number/displacement from the base address. So, indirecting it with * is same as s[i]. i[s] may be surprising. But in the case of C it is same as s[i]. 3 . main(){  float me = 1.1;  double you = 1.1;  if(me==you) printf("I love U"); else printf("I hate U"); } Answer: I hate U Explanation : For floating point numbers (float, double, long double)
Post a Comment
Read more