40 6th grade math extension calculation questions

"Now A does it for 16 days, and then B does it alone for 12 days" can be regarded as A and B working together for 12 days, and A doing it alone for 16 12 4 days.

A and B cooperation can be completed in 12 days: 12 1 24 1 2 A can be completed in 4 days alone: 1 2 5 1 2 1 10 A's ergonomics: 1 10 4 1 40

Ergonomics of B: 1 24 1 40 1 60

A completes this batch of parts more than B every day: 1 40 1 60 1 120 This batch of parts has: 3 1 120 360 (pcs).

A per hour of water injection is regarded as "1";

B water injection per hour: 1 2 (20 60)-1=3 2-1=1 2;

B Fill the pool separately Required: 1 1 2 = 2 hours.

Solution: The efficiency of A is 1 60, and the sum of the efficiency of A and B is 1 40

Then the efficiency of B is 1 40-1 60 = 3 120-2 120 = 1 120

1/2 divided by 20 equals 1/40, 1/40 minus 1/60 equals 1/120, and 1 divided by 1/120 equals 120

Because a+a=a+c

So a=c because b+b+b+b+b+b+b+b+b=a+c

i.e. 7b = 2c

So c = so a+a+a+b+b+b+b+b3c+4b

4 and 1 7 Cs

1.The number of people who subscribe to the math newspaper is 45 * 4 5 = 36

The number of subscribers to the newspaper is 45 * 2 3 = 30

So the number of people who ordered both was 36 + 30-45 = 21 people 2, and Xiao Ming added 1 2 water for the first time.

The second time I added 1 to 3 water.

So a total of 1 2 + 1 3 = 5 6 water was added.

And he added milk for 1

So he drank more milk than water.

If you don't understand, you have to ask Oh ( o

Person 2Xiao Ming drank a total of one glass of milk, and the amount of water was 1 2 cups plus 1 3 cups, a total of 5 6 cups, so Xiao Ming drank a lot of milk.

There were 21 subscribers to both newspapers.

The total amount of milk is 1, and the water is 1 2 + 1 3 = 5 6, and there is more milk.

Each item under observation is (n+1) 3-n, and you can try it all at once!

Apply the formula for summing continuous cubes and equal difference sequences.

1x2+2x3+3x4+4x5+..2002x2003

A and B respectively set off from AB and traveled in the same direction, their speed ratio was 3:2 when they started, after the encounter, A's speed increased by 1 5, B's speed increased by 2 5, and when A arrived at B, B was still 26km away from A. How many kilometers are the two places apart?

Let AB and the two places be separated by x kilometers.

2/(3+2)x]/[3×(1+1/5)]=[3/(3+2)x-26]/[2×(1+2/5)]

x/9=3x/14-130/14

13x/126=130/14x=90

A, B, and C went shopping together, and 1 2 of A's money was equal to 1 3 of B's money, and 3 4 of B's money was equal to 3 5 of C's spending, and C spent 98 yuan more than A, and asked them how much money they had spent.

490 yuan. A and B run a 100-meter run (assuming their speed remains the same), and when A runs 75 meters, B runs 60 meters. So, how many meters did B run when A reached the finish line?

80 meters. 1/6 + 1/12 + 1/24 + 1/48 + 1/96 + 1/192

The number of factor 5 determines the number of 0 at the end.

2008 5 = 401 (rounded).

2008 25=80 (rounded).

2008 125 = 16 (rounded).

2008 625 = 3 (rounded).

401 + 80 + 16 + 3 = 500.

1*2*3*4*5*6*……There were 500 zeros at the end of 2008

If a car drives from A to B, if the speed is increased by 20%, it can arrive 1 hour earlier than the original time, and if it travels 120 kilometers at the original speed and then increases the speed by 25%, it can arrive 40 minutes in advance.

40 minutes = 2 3 hours.

Original time: 1 [1-1 (1+20%)] = 6 hours.

The original speed [120-120 (1+25%)] 6-2 3-6 (1+25%)] = 24 8 15 = 45 km/h.

A and B are 45 6 = 270 kilometers apart.

The average score of the class in the final test of mathematics for class four (1) is 92 points, the number of boys who took the test is 18, the average score is 89 points, and the average score of girls is 94 points

92-89) 18 (94-92) = 27 people.

Chen Ming traveled 38 kilometers a day on flat roads and 23 kilometers a day on mountain roads, a total of 450 kilometers in 15 days. Asked how many kilometers of mountain roads he had walked during this time.

184 km.