# Gr.11 Math

posted by .

A large company has a phone tree to contact its employees in case of an emergency factory shutdown. Each of the five senior managers calls three eployees, who calls three other employees and so on. If the tree consists of seven levels, how many employees does the company have?

Could someone explain to me how to solve this? Which geometric formula would I have to use?

• Gr.11 Math -

THE first layer 5
second layer 5x3
third layer 5x3x3
see the pattern?5*3^(n-1)
where n is the layer.
employees total is the sum of all of these. Looks like a geometric series..

• Gr.11 Math -

If you call the five senior managers as the first level, then in the second level there would be 15 and in the third level there would be 45

so you want the 7th term in this sequence, not the sum of 7 terms (because you would be counting the same people again and again)

so a=5, r=3, and t(7) = ar^6 = 5(3)^6 = 3645

check my arithmetic.

• Gr.11 Math -

Use the formula

Sn = a(r^n-1)
--------
r-1

• Gr.11 Math -

s7=5(3^7-1)/3-1
=5465

## Similar Questions

1. ### Algebra

ABC phone company charges \$18 per month plus 7 cents per minute of phone calls. XYZ phone company charges \$9 per month and 10 cents per minute of phone calls. How many minutes of phone calls should be made each month to make the costs …
2. ### Pre Algebra

A phone company charges \$27.95 monthly fee and .12/min. for local calls. Another phone company charges \$12.95 a month and .32/minute for local calls. For what number of minutes of local calls is the cost of the plans the same?
3. ### Algebra

ABC phone company charges \$16 per month plus 8¢ per minute of phone calls. XYZ phone company charges \$10 per month plus 11¢ per minute of phone calls. How many minutes of phone calls in a month make XYZ phone company the better deal?
4. ### statistics

A firm has 30% of its service calls made by a contractor, and 15% of these calls result in customer complaints. The other 70% of the service calls are made by their own employees, and these calls have a 5% complaint rate. Use Bayes’ …
5. ### Math (Functions)

A large company has a phone tree to contact its employees in case of an emergency factory shutdown. Each of the five senior managers calls three eployees, who calls three other employees and so on. If the tree consists of seven levels, …
6. ### Math (Functions)

A large company has a phone tree to contact its employees in case of an emergency factory shutdown. Each of the five senior managers calls three eployees, who calls three other employees and so on. If the tree consists of seven levels, …
7. ### math

Hadley's softball team has a phone tree in case a game is cancelled.The coach calls 3 players. Then each of those players calls 3 players and so on.How many players will be notified during the 3rd round of calls?
8. ### Algebra 1 thx

Hadley's softball team has a phone tree in case a game is canceled. The coach calls 3 players. Then each of those players calls 3 players, and so on. How many players will be notified during the third round of calls?
9. ### Math/Solve

ABC phone company charges \$17 per month plus \$0.03 per minute of phone calls. XYZ phone company charges \$8 per month plus \$0.06 per minute of phone calls. How many minutes of phone calls in a month make XYZ phone company a better deal?
10. ### Communication in the Workplace

Imagine that you have taken a new job as head of Human Relations (HR) for an up-and-coming software firm. Your 150 employees are hip, smart and tech savvy. They are also big cell phone users. Cell phones are an important tool for your …

More Similar Questions