**I. 257.** The management of a certain store analyses shopping habits. Above the ground floor, the store has two floors and one staircase with two escalators, connecting the floors by going upstairs and downstairs. Surveillance cameras observe people entering and exiting the ground floor, and going upstairs and downstairs. Results are summarized quarter-hourly, from the morning opening until the evening closing, that is, between 8:00 and 20:00.

The text file `szamlalas.txt` (tabulator separated file in UTF-8 encoding, downloadable from our web page) contains the total number of customers in each quarter hour, collected by the six cameras. (In the *example,* ```0be`'' and ```0ki`'' abbreviate the number of customers entering and exiting the ground floor, ```1fel`'' and ```1le`'' stand for the number of people going up to the first floor and coming down from the first floor, ```2fel`'' and ```2le`'' denote similar numbers for the second floor.)

*During your solution you should *

-- *use formulae, functions or links, *

-- *place auxiliary computations (if any) to the right of column* `R`.

1. Open the file `szamlalas.txt` such that its first data piece is put into cell `A1`. The sheet should be saved as `i257` in the default format of the spreadsheet application.

2. You should generate the appropriate time intervals from the opening until closing according to the *example* (see column ```Időpont`'').

3. Cells in columns `H`, `I`, `J` and `K` should contain the number of customers at the end of the actual interval on each floor: column `H` for the ground floor (```Földszint`'' in the *example*), `I` and `J` for the first and second floors (```1. emelet`'', ```2. emelet`'') and `K` for the complete store (```Összesen`'').

4. According to the above data, you should answer the following questions.

a. Cells `N2:P2` (```Látogatók száma összesen`'') should contain the total number of customers that visited each floor during the whole day.
b. Cells `N3:P3` (```Arány az összes vásárlóhoz`'') should contain the relative percentages on each floor (100% corresponds to the total number of customers in the store), using a cell format with zero decimal digits.

c. Cells `N4:P4` (```Legtöbb vásárló egyszerre`'') should count the maximum number of people present simultaneously on each floor.

d. Cells `N5:P5` (```Legtöbb vásárló időpontja`'') should display the time interval during which the most people were present simultaneously on each floor.

5. Computed values should appear in blue color.

6. Cells in the first row should be formatted according to the *example.* Appropriate column widths should be set so that all data is visible.

7. Create a bar chart on the sheet showing the total number of people in the store in each quarter hour, but

-- the chart should not have a legend,

-- its title should be ```Summary`''

-- and every second quarter hour should be visible on the horizontal axis.

Your spreadsheet (`i257.xls`, `i257.ods`, ...) together with a short documentation (`i257.txt`, `i257.pdf`, ...) -- also describing the name and version number of the spreadsheet application -- should be submitted.

(10 points)

**Deadline expired on 10 February 2011.**

Leitereg András (Budapest, Veres Péter Gimnázium 10. osztály) megoldását közöljük: i257.xls