More Brain Teasers

Census Taker

A census taker approaches the man of the house and asks the ages of his children.  "I don't know," said the man, "the product of their ages is 72 and the sum of their ages is the house number."

The census taker backed to the sidewalk, looked at the house number and returned to the man saying, "Okay, I still don't know the ages of the children."

"Oh," said the man, "Iforgot to tell you--the oldest one likes chocolate pudding."

The census taker then wrote the ages of the three children.  What are the ages of the three children?  No, you don't get to know the house number.

Earnings

You talk your board of education into an agreement where you earn 1 cent the first day, 2 cents the second day, 4 cents the third day, 8 cents the fourth day, and continually double each day thereafter.  How much would you earn at the end of 31 working days?

Magnet School

A new wing has been added to the Magnet School for Math, Science, and Technology, so that the student population can be increased by 142 students, 480 to 622.  The new sophomore class will have 142 more students than the graduating senior class.  To accommodate the increase, the size of the faculty is to be increased by seven.  There is a great deal of discussion about which departments should get the extra teachers.  At the time of the increase, the teacher population was:
    6 Math                      5 English
    3 Chemistry            3 Foreign Language(1 Spanish, 1 German, 1 French)
    3 Physics                1 Music
    4 Biology                 1 Art
    4 Social Studies

Should every department each receive one teacher, or does the demand on some departments argue that they should receive two new teachers while other departments get none?  Should any department get three new members?  Given the present number of students taking classes from each department, houw would you apportion the seven new faculty members to departments most fairly?  Explain why your decision is fair.

Department                                10th        11th        12th        Total
Art                                                21            33            15            69
Biology                                        198          95            26           319
Chemistry                                    59           126          109         294
English                                         183         155          151         489
French                                          41           32             49          122
German                                        19           22             10            51
Mathematics                                184         201           262         647
Music                                            20           26              49           95
Physics                                         50           58             183         291
Social Studies                              183        131            59          373
Spanish                                         51           26             33           110

Challenge--Army Troop

An army troop 25 miles long begins marching at daybreak.  At dusk the troop stops marching.  The trooper that began the day at the end of the 25 mile long line has marched 25 miles.  Each day a runner begins at the rear of the line and runs to the front of the line and returns to the rear.  He repeats this continuously until the troopers camp for the night.  How many miles does the runner run in the course of a day?  You may not be able to calculate an exact number.  Describe your process for solving the problem.

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