How do you explain mental math to multiple two numbers

David started across a lake 15 miles wide in his fishing boat at 10 miles per hour. He had to row the rest of the way at only 5 miles per hour after his motor went out.

Which of the following is a possible consequence of sampling from a population? O Every sample from a population has a predetermined accuracy. O Sampling error can be eliminated if we have large enough samples.

Factor the GCF: -12x4y - 9x3y2 + 3x2y3 A. - 3x2y (4x2 + 3xy - y2) B. 3x2y (-4x2 + 3xy - y2) C. - 3 (4x2y + 3x3y2 - x2y3) D. - 3x2y (-4x2 - 3xy + y2)

An angle measures 16° more than the measure of its supplementary angle. What is the measure of each angle?

In a middle school with 200 students there are 40% girls. 20% of the students wear glasses. It is also known that 10% of the boys wear glasses. 1. How many boys are in this school? 2. How many girls don't wear glasses 3.

Does the fraction 1/2 make the equation 1/34 + 8/17 = 1/2 true?

Remember that you can multiply by the reciprocal of the divisor when you divide by a fraction. find each quotient. simplify if possible 1. 1/3:2 2. 1/7:7 3. 1/2:8 4. 1/8:2

Draw a area model to solve the following. Find the value of the following expression. 30 * 60

15 nickels are stacked vertically how many inches tall is the stack

Isabelle desperately wants an I-Pod Touch. After researching on-line she discovers the l-Pod she wants is $300. After begging her parents to buy the l-Pod for her, they make a deal with Isabelle.