What was wrong with my calculation?

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SUMMARY

The discussion centers on a physics problem involving a collision between an 8kg object and a 10kg object. After the collision, the 8kg object moves south at 4m/s, while the 10kg object's velocity is calculated to be 12.4 m/s at an angle of 14.9 degrees North of East. The percentage of kinetic energy lost in the collision is determined to be 7.2%. The user encountered confusion regarding the calculation of kinetic energy and the interpretation of symbols in the equations provided.

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Homework Statement



a 8kg object moving east at 15m/s at a frictionless horizontal surface collides with 10kg object that is initially at rest. After collision, the 8kg object moves south at 4m/s.
a)what is the velocity of 10kg object after collision?
b)what percentage of the initial kinetic energy is lost in the collision?
The answer is a)12.4 m/s at 14.9 angle N of E b)KE lost=7.2%

Homework Equations



%KE lost = (KE1 - KE2)/(KE1)*100
KE1 = 1/2*m1*v1**2
KE2 = 1/2*m1*v2**2 + 1/2*m2*v3**2
Someone gave me this equation. But I cannot understand lots of symbols such as ** here.
Note:v3 is velocity of 10kg object after collision, which is 12.4m/s.


The Attempt at a Solution



I already solved a) and I was solving b) now. I pugged my value in the equation above assuming that ** means squared. And my answer was 7.4!
how could this can happen? I tried again and again and 7.4 kept came out instead of 7.2
Does my textbook is wrong of that equation is wrong? If the equation is wrong, pleas tell my the fixed form.
 
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Yes, I make it 7.4 or 7.5 also.
 
whew! I thought I made a huge mistake in the middle! I must tell my prof that the answer 7.2 is wrong.
 

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