What is the sum of all the even numbers bigger than (-10) and smaller than 12?
Answer(s): B
This is a series of numbers with a constant spacing between them. The first number is (-8) and the last is (10), there are 10 numbers altogether. The formula for such a series is: ((-8 + 10) x 10)/2 = 10.The second way to answer such a question is to write the numbers and add them.
The value of an “Aerosoul” stock changes according to the following method:At the end of each month her value is doubled but due to commission the stock’s value is decreases by $10. If the value at the beginning of January is $A, what would be her value at the end of February?
Answer(s): C
At the end of January her value is 2A – 10.At the end of February her value is (2 x (2A – 10) – 10 = 4A – 30).
An Ameba is an organic life form that divides into two Amebas each round hour. If at a certain round hour, two Amebas were placed in a jar, how many Amebas will be in the jar in N hours?
Let’s find the number of Amebas in the first hours. After one hour (N=1) there will be 4 Amebas.After two hours (N=2) there will be 8 Amebas. After three hours (N=3) there will be 16 amebas. Therefore the formula that fits this series is 2N+1.
Alfa, Beta and Gamma are inner angles in a triangle. If Alfa = Beta + Gamma, what can’t be the size of Beta?
Answer(s): D
If Beta is 90 degrees than Alfa is bigger than 90 and the sum of the angles in the triangle will be bigger than 180 degrees.
In a triangle, one side is 6 Cm and another side is 9 Cm. which of the following can be the perimeter of the triangle?
The third side of the triangle is larger than 3 (The difference between the other two) and smaller than 15 (The sum of the other two).The perimeter is between (6+9+3 = 18) and (6+9+15 = 30). The only answer that is in this range is B.
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