Rational means that the number can be written as exact number or with a repeating decimal. Which of the above is either a terminating or repeating decimal?

# All posts by mathconfidence

# February 2019 Brain Puzzler Solution

Q: A traffic light has a cycle through green, yellow, red, green, yellow, red, etc.

Red and green are each 30 seconds with a 3 second yellow inbetween.

What is the probability that while Amir is watching during a random 3 second interval that the color changes?

A:

9/63 = 1/7

It is a 63 second cycle.

The light changes at t=30, t = 33 and t = 63 given three three second intervals:

[27,30] and [30, 33] and [60,63] is a total of 9 seconds out of the 63 second interval

# Jan 2019 Algebra I Regents #2

This question asks students to substitute or plug in -3 for x so

g(-3) = -2(3)^2 + 3(-3) being careful about order of operations 🙂

Students can check their work by using the TI-84

# January 2019 Brain Puzzler Solution

Q: On the way to catch an international flight, Sabina drives 35 miles per hour for an hour and realizes she will be an hour late if she continues at this speed. If she increases her speed by 15 miles per hour for the remaining part of the drive she will arrive 30 minutes early. How far is her home from the airport?

A: 210 miles

She already covered 35 miles. She has d miles left at 50 miles an hour.

Her time left to travel would be d/50 and because she will arrive an hour late vs a half hour early, there is a 1.5 hour difference between her time this faster speed and her time at the slower speed. So the time of d/50 is 1.5 less than d/35.

We can write this as d/50 = d/35 – 1.5 OR d/50 + 1.5 = d/35

When you solve this, you will get that the remaining distance is 175 miles plus we have to add the original 35 miles. It would have taken Sabina 6 hours in total at 35 mph to cover the 210 miles but instead takes her only 4.5 hours — the first hour that she drove at 35 mph (35 miles) and the next 3.5 hours at 50 mph (175 miles).

# Best Wishes to Regents Exam Takers

Dear New York High Schoolers,

Best on your Regents exams this week.

Make sure you get to school early and eat a good breakfast!

Do not leave early: Spend all the allotted time (3 hours — unless your IEP is for more time)

Eat a good breakfast

Read carefully

Go over the entire exam after you finish and check your work

Sincerely,

Robin the Math Lady