In the number 777,777, the 7 in the tens place is 1/10 the value of the 7 in the place?

Aproduction manager test 10 toothbrushes and finds that their mean lifetime is 450 hours. she then design sales package of this type of toothbrush. it states that the customers can expect the toothbrush to last approximately 460 hours. this is an example of what phase of inferential statistics

What is the best approximation for the area of a circle with a radius of 4 m ? use 3.14 to approximate pi

Can someone tell me if this is perpendicular? !