1. Xtra Edge February 2012 - Career Point

should be bought to meet the requirement and the cost
be minimum. Solve the problem graphically.
OR
A furniture dealer deals only in two items-tables and
chairs. He has Rs.10,000 to invest and a space to
store at most 60 pieces. A table costs him Rs. 500
and a chair Rs.200. He can sell a table at a profit of
Rs.50 and a chair at a profit of Rs.15. Assume that
he can sell all items that he buys. Using linear
programming formulate the problem for maximum
profit and solve it graphically.
28. A wire of length 36 m is to be cut into two pieces.
One of the pieces is to be made into a square and
other into a circle. What should be lengths of two
pieces, so that combined area of the squared and
circle is minimum.
29. Solve the system of equation by using matrix
method.
2 3 10 4 6 5
+ + = 4 ;
– + = 1 ;
x y z
x y z
6 9 20
+ – = 2
x y z
Brain Teaser
Pears - There are a few trees in a garden. On one of
them, a pear tree, there are pears (quite logical). But
after a strong wind blew, there were neither pears on
the tree nor on the ground. How come?
Pears – Solution At first, there were 2 pears on the
tree. After the wind blew, one pear fell on the ground.
So there where no pears on the tree and there were no
pears on the ground.Another possible solutions: The
wind blew so hard that the pears fell of the tree and
blew along the ground into the water or hovering in
the air in a tornado.
1. Emeralds have been produced synthetically in
labs since 1848 and can be virtually
indistinguishable from the genuine article.
2. In the last 200 years the use of metals has
increased as scientists have discovered new ones:
until the 17th Century only 12 metals were
known - there are now 86.
3. The only person to have an element named after
him while still alive was Glenn Seaborg, the
most prolific of all the element hunters.
4. Traffic lights with red and green gas lights were
first introduced in London in 1868.
Unfortunately, they exploded and killed a
policeman. The first successful system was
installed in Cleveland, Ohio in 1914.
5. In 1998, design student Damini Kumar at South
Bank University patented a teapot with a special
grooved spout, which she claims virtually rules
out dribbling.
6. Even though most items in the home today are
technologically up to date, most of us are still
using the standard light bulb designed in 1928!
7. A chest x-ray is comprised of 90,000 to 130,000
electron volts.
8. The strength of early lasers was measured in
Gillettes, the number of blue razor blades a given
beam could puncture.
9. The first commercial radio station in the United
States, KDKA Pittsburgh, began broadcasting in
November 1920.
10. A British rocket attack on US soldiers is
celebrated in the lyrics of the US National
Anthem.
11. Until the late 1800s, it was forbidden for women
in the United States to obtain a patent, so if a
woman had invented something she would file
for a patent under her husband or father's name.
For this reason, the number of early female
inventors remains a mystery.
XtraEdge for IIT-JEE 73
12. Milt Garland, a 102 year old engineer, invented a
technology that forms ice on the exterior of a
casing instead of inside it, which is used to create
indoor ice rinks.
FEBRUARY 2012