Anationwide test taken by high school sophomores and juniors has three sections, each scored on a scale of 20 to 80. in a recent year, the national mean score for the writing section was 51.2. based on this information, complete the folloiwng staements about the distribution of the scores on the writing section for the recent year.
1. according to chebyshev's theorem, at least % fo the scores lie within 2.5 standard deviations of the mean, 51.2.
2. suppose that the distribution is bell shaped. if approximately 99.7% of the scores lie between 23.6 and 78.8, then the approximate value of the standard deviation for the distribution, according to the empirical rule, is

x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

step-by-step explanation:

last month maria hiked the 5-mile mountain trail a number of times and she hiked the 10-mile canal trail several times. let x represent the number of times she hiked the 5-mile trail, and let y represent the number of times she hiked the 10-mile trail. if she hiked a total of 90 miles, which equation can be used to find the number of times maria hiked each trail? x + y = 90 5x – 10y = 90 90 – 10y = 5x 90 + 10y = 5x

she would want to sell 10 full-year subscriptions and at least 9 half-year subscriptions to get a total of at least $300. 

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step-by-step explanation:

mark brainliest!