A school club uses a telephone chain to inform members of changes in plans. The club president calls 2 members, each of whom calls 2 members, and so on. The process must be repeated 5 times. How many members are in the club?

63 members

Step-by-step explanation:

Since each person calls 2 persons each, there is an exponential increase of 2 for each level. Since it starts with the president as 1 person, and increases exponentially by 2 for each level of phone call, we have a geometric progression of first term, a = 1 and common ratio r = 2. Since the process of phone calls must be repeated 5 times, our last term is 2⁵. So, our geometric progression is 2⁰ + 2¹ + 2² + 2³ + 2⁴ + 2⁵ = 1 + 2¹ + 2² + 2³ + 2⁴ + 2⁵

We now sum the geometric progression

The sum of a geometric progression with r > 1 is

S = a(rⁿ - 1)/(r - 1)

substituting r = 2, a = 1 and n = 6 since we have 6 terms, we have

S = 1(2⁶ - 1)/(2 - 1)

= (64 - 1)/1

= 63

So, we have 63 members in the club.

We could have also found this by summing up individually the terms in the series. We have 1 + 2¹ + 2² + 2³ + 2⁴ + 2⁵ = 1 + 2 + 4 + 8 + 16 + 32 = 63

Step-by-step explanation:

45/11 miles per day or ~4.091 miles per day

Step-by-step explanation:

3 inches per second

24 hours in a day

60 minutes in 1 hour

60 seconds in 1 minute

Amount of inches per minute: 3 x 60 = 180 inches

Amount of inches per hour: 180 x 60 = 10,800 inches

Amount of inches per day 10,800 x 24 = 259,200 inches

To find the number of feet that 259,200 inches is, divide by 12.

259,200/12 = 21,600 feet per day

To find the number of miles that 21,600 feet is, divide by 5280.

21,600/5280 = 45/11 = 4.09090909091 = ~ 4.091

So, an ant could walk 45/11 miles per day or ~4.091 miles per day if it walked without taking a break.