FOR CHILDREN

PROBLEM # 1
Below is an equation that isn't correct yet. By adding a number of plus signs and minus signs between the digits on the left side (without changing the order of the digits), the equation can be made correct.

123456789 = 100

One way of making the equation correct is 1+2+3-4+5+6+78+9=100.
Give another way of making the equation correct.

FOR GROWNUPS

PROBLEM # 2
The height of a triangle is increasing at a rate of 2 cm/sec, while its area is decreasing at a rate of 2 sq.cm./sec. Find the rate at which the base of the triangle is changing when the height of the trainagle is 20 cm and the area of the triangle is 80 sq.cm.

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SOLUTIONS TO PROBLEMS ON 11/30/06

FOR CHILDREN

PROBLEM # 1
A race car driver drove, on a 4 km long race course, at an average speed of 120 km/h for the first 2 km. How fast does he have to go the second 2 km to average 240 km/h for the entire course?

SOLUTION
Not  possible or infinite speed.

FOR GROWNUPS

PROBLEM # 2
Suppose triangle ABC has the property that angle C = 2 x angle A. If side a = 49 abd side b =72, find side c.

SOLUTION 
77.

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