standard_description: Add and subtract within 1000, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method. Understand that in adding or subtracting three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones; and sometimes it is necessary to compose or decompose tens or hundreds.
problem_activity: Problem 1
Below is a normal distribution that shows the height of 8-year-old boys in inches. The relative frequency of each height is shown along the
$${y-}$$
axis, and the height, in inches, is shown along the
$${x-}$$
axis.
The mean is 50 and the standard deviation is 2.
[IMG]
Estimate the percent of 8-year-old boys chosen randomly who will be shorter than 53 inches.
Problem 2
The mean combined score for last year’s SAT was 1083 with a standard deviation of 193. The mean and the standard deviation are based on students who took the SAT across the nation.
If you took the SAT and scored a combined score of 1100, what percent of students who took the SAT scored below you?


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