3rd grade: Math problems for March 1 2011

Problem #1

If 24 gallons of water are poured into an empty tank, then 3/4 of the tank is filled.

How many gallons does a full tank hold?

To see solution click here




Problem #2

A train can hold 78 passengers. The train starts out empty and picks up 1 passenger at the first stop, 2 passengers at the second stop, 3 passengers at the third stop, and so forth.

After how many stops will the train be full?

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Problem #3
The number of two-dollar bills I need to pay for a purchase is 9 more than the number of five-dollar bills I need to pay for the same purchase.

What is the cost of the purchase?

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Problem #4
The last Friday of a particular month is on the 25th day of the month.
What day of the week is the first day of the month?

Here is the video with almost correct solution. Please find the error.
See here



Problem #5

The age of a man is the same as his wife's age with the digits reversed. The sum of their ages is 99 and the man is 9 years older than his wife.

How old is the man?

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Problem #6

D is the sum of the odd numbers from 1 through 99 inclusive, and N is the sum of the evn numbers from 2 through 98 inclusive:
D = 1+3+5+ ...+99
and
N = 2+4+6+...+98

Which is greater, D or N, and by how much?