SSAT Math Question 392: Answer and Explanation

Home > SSAT Test > SSAT Math Practice Tests

Test Information

Question: 392

3. Kelsey is participating in a walk-a-thon to raise money for a charity. Her parents are going to contribute twenty cents after she walks one mile, forty cents after she walks two miles, and sixty cents after she walks three miles. If her parents continue to donate money in this manner, how much money will Kelsey's parents contribute to her charity if Kelsey walks 26 miles?

  • A. $68.00
  • B. $68.20
  • C. $70.00
  • D. $70.20

Correct Answer: D

Explanation:

D

The sum of a series of n evenly spaced numbers where S1 is the first number and Sn is the last number is given by the expression n. In this case, you are told that there are 26 evenly spaced numbers, and that the first number is 20 cents. You need to figure out the last number. The pattern shows that the day (1, 2, 3, etc.) is multiplied by 20 cents, so on the 26th day, the value is $5.20. Plug these values into the formula (using dollars or cents): 26 = 70.20.

You can write out the donations and add them up, but this may be time consuming and result in a careless error.

Previous       Next