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Find some math problems in the eighth grade
1. A truck is 600 meters long and travels eastward at a constant speed of 54 kilometers per hour. A bus, 400 meters long, runs eastward at a constant speed of 72 kilometers per hour on another parallel track. How many seconds does it take for a bus to overtake a truck?

The school buys prizes with a sum of money. If you take 1 pen and 2 diaries as one prize, you can buy 60 prizes. If you use 1 pen and 3 diaries as prizes, you can buy 50 prizes. How much can you buy if all this money is used to buy pens or diaries?

Xiaoli and Xiaoxue set out from A and B respectively at the same time.

Go in the opposite direction

Return to your original place immediately after meeting.

It took 48 minutes each time.

If Xiaoxue leaves earlier than Xiaoli 10 minutes.

Xiao Li met Xiao Xue after leaving for 20 minutes.

How long does it take Xiaoli to get from A to B and Xiaoxue to get from B to A? (Use the binary fractional equation. )

3. A certain area has carried out the activity of "going to the countryside through science and technology" for four years.

In the first year, 654.38 million people received scientific and technological training.

In the fourth year, 13438+00000 people received scientific and technological training.

Suppose in these four years,

The number of people receiving scientific and technological training has the same growth rate every year.

Seek this growth rate. (Use the fractional equation. )

Party A and Party B each process 300 pieces.

A takes less time 1 hour to finish the task than B.

Improved operation method

The production efficiency has doubled.

Results It takes 7/6 hours for B to complete 300 parts than for A to complete 250 parts.

Ask Party A and Party B how many parts are processed per hour (unless there is an accident).

Or fractional equation)