Tricia receives a $5 allowance every week. she also earns $6.50 for every hour that she baby-sits. next week, she wants to earn at least $21.25 to buy a present. how many hours will she need to baby-sit?
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Mp model with mathematics explain how the number of text messages dario sent and the cost form an arithmetic sequence.then write an expression to find dario's text messaging bill if he sends n text messages over 250.

Rockwell hardness of pins of a certain type is known to have a mean value of 50 and a standard deviation of 1.1. (round your answers to four decimal places.) (a) if the distribution is normal, what is the probability that the sample mean hardness for a random sample of 8 pins is at least 51?

Vinay constructed this spinner based on the population of teachers at his school according to vinays model what is the probability that he will have a male history teacher two years in a row