Math

posted by Ethan

1. Daniel wants to save at least 20 dollars by putting pennies in a jar daily. On first day, he puts one penny into the jar. The second day he puts 2 pennies into the same jar. On the nth day he pus n pennies into the same jar. Which day is the first day on which he has at least 20 dollars in thejar? (1 dollar=100 pennies) a. 60 b. 61 c. 62 d. 63 e. 64
I tried the sum equation but I got 1334 which is no one of the choices.

2. The first term of a sequence is 12, and each term after the first is 2 less than the preceding term. If n is a positive integer, which of the following could be the sum of the first n terms of the sequence? a. -14 b. -2 c. 28 d. 31 e. 81

3. "123...91011...3" If the positive integers(to the left) are written one after another as shown until the eighth occurence o the digit 3, how many digits are in the number? a. 29 b. 33 c. 39 d. 48 e. 57

  1. Steve

    #1
    n(n+1)/2 >= 2000
    n^2+n-4000 > 0
    n > 62.7
    So, 63 days

    #2 clearly the sum must be even.
    sum = n/2 (24+(n-1)(-2))
    http://www.wolframalpha.com/input/?i=n%2F2+%2824%2B%28n-1%29%28-2%29%29+for+n%3D1+to+50

    #3
    1-digit #'s: 3
    teens: 13
    20's: 23
    30's: 30-33

Respond to this Question

First Name

Your Answer

Similar Questions

  1. math

    Mr. Samuel has 150 pennies in two jars. There are 40 more pennies in one jar than the other. How many pennies are in each jar?
  2. math

    Mr. Samuel has a 150 pennies in two jars there are 40 more pennies in one jar than the other, how many pennies are in each jar
  3. 3rd grade

    Mr Samuel has 150 pennies in two jars. There are 40 more pennies in one jar than in the other. How many pennies are in each jar?
  4. Math Qs. Check!!!!!!

    Jake puts pennies into a jar each morning and lets his brother take haft of the pennies out each morning. Jake put 10 pennies into the empty jar on Monday morning. On Tuesday he put in 15 pennies. One Wednesday he put in 12 pennies. …
  5. math

    A jar contains 120 pennies. A bigger jar contains 1 1/4 times ss many pennies. What is the value of the pennies in the jar?
  6. math

    A jar contains 133 pennies. A bigger jar contains 1 2/7 times as many pennies. What is the value of the pennies in the bigger jar
  7. Math

    1. Daniel wants to save at least 20 dollars by putting pennies in a jar daily. On first day, he puts one penny into the jar. The second day he puts 2 pennies into the same jar. On the nth day he pus n pennies into the same jar. Which …
  8. Math

    Bill is saving money in an empty jar. The first day he puts in a certain amount of money. Every day after the first he puts in 2 more dollars than the amount he put in on the previous day. After 10 days he has put 200 dollars in the …
  9. Math Help!

    I apologize for all these questions but I really need to get them done fast so I appreciate if you tried to answer some of them! 1. Bill is saving money in an empty jar. The first day he puts in a certain amount of money. Every day …
  10. Math

    There are 100 coins in a jar and 10 are dimes. The rest are pennies and nickles. There are twice as many pennies as nickels. How many pennies and nickles are in the jar?

More Similar Questions