Is a blood pressure of 83 over 50 ok for a ten year old girl?

Cuff size??: You won't get an accurate reading on most 10 year old kids if you're using a home blood pressure monitor. Young kids need small cuffs for the most part. A too large cuff will give you low BP readings. Likewise a cuff too small will give you elevated BP readings.

Yes: A normal, healthy 10 year old child can have 83/50 blood pressure, unless she has some medical illness or symptoms.