Answer:

Step-by-step explanation:
The formula of the circumference of a circle is
.
The length of an arch can be found by using the ratio of circumference to the arc.
First, find the circumference of the circle:

Then you find the ratio:
The length of the arc is 90/360, which is 1/4, of the circumference.
Finally, find the length of the arc:
or 
I hope this helps :)
Answer:
423
Step-by-step explanation:
349+74=423
Answer:
3.90 meters.
Step-by-step explanation:
Since Amy needs ribbon for her art project, and she plans to buy 3.84 meters of that material, but the store only sells said product by the tenth of a meter, in order to get closer to the desired size she will have to buy 39 pieces of 10 cm (one tenth of a meter), that is, she must buy 3.90 meters, of which there will be 6 centimeters of the product left over.
Answer:
Type I error
Step-by-step explanation:
A type I error occurs if the null hypothesis is rejected when it is actually true.
Type I Type II
Reject null when true Fail to reject null when not true
Null hypothesis: ∪ = 30%
Alternative hypothesis: ∪ > 30%
The researchers concluded that more than 30% of first-grade students at this school have entered the concrete operational stage of development and they rejected the null hypothesis.
However, a census actually found that in the population of all first graders at this school, only 28% have entered the concrete operational stage.
A type I error has been made because in actuality the null hypothesis was true but was rejected.