How old do an average 12 year old get their period?

What is one-eighth times three? If P(A)0.003 what is the value of P(A)? Is 2x 3x 3y is an example of addition of monomials? What number is equal to 4.4 million dollars? What types of angles are equal beginning with o? What is the missing side length of an irregular quadrilateral with side lengths 23.3cm 30.4cm and44.9cm If the perimeter is equal to the perimeter of a regular pentagon with side length 26cm? What are the regular polygons that make up a tesselation? What is the factor tree for 45 and 81? Can a trapezoid rotate in 90 degrees? Unequal in degrees alike in size what is it? What speed to go 50 miles in 9 hours? What are the x-intercepts of unit circle in sin? How much water is in 800g measurement? What is increased development? What is 8 meters long? How can a ratio be used to compare quantities? How is 0.00432 expressed in scientific notation? What is the gcd of 68 and 35? What are the measurements for A5 size paper? How many dollars is 10 pounds?