John drove the first half of the road AB with the speed 40 km/h and drove the rest part of the road with 60 km/h. Calculate John's average speed on the whole journey.
Answer: km/h
K
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21 tháng 3 2016
Quãng đường John lái xe được trong 3.5 giờ đầu là 64 x 3.5 = 224 (km)
Quãng đường John lái xe được trong 1.5 giờ cuối là 60 x 1.5 = 90 (km)
Tổng quãng đường John lái xe được trong suốt chuyến đi là 224 + 90 = 314 (km)
25 tháng 3 2016
Bob lái xe từ thành phố đến thành phố P Q. Ông đã Đi 36km đầu tiên với tốc độ trung bình 54 km / h. Ông đã Đi 96 km còn lại ở tốc độ trung bình 72 km / h. Tìm tốc độ trung bình của Ngài cho toàn bộ chuyến đi.
Trả lời: km / h.
23 tháng 8 2018
Read the story. Fill in the blank with one suitable word.
John's parents gave him a red drum for his eight birthday. When John (0)...opened....his present early that morning, he was very (1).........surprised.........to see a drum inside! He started to play it very loudly. He played it all morning and then after lunch he wanted to play it again. But his mum felt ill. She had a bad (2)....headache..... because John and his drum were so noisy. His dad said, "John, if you want to play your drum, go outside please." John went into the garden and played his drum there. After fives minutes, he (3)........heard........some lovely music. He went out into the street and saw a lot of people there. It was the circus! They drove into town in their lories and trucks. The (4)......driver..........of the first truck stopped when he saw John. John jumped on the back of the truck and (5)........went ........ into town with them. He played his drum all the way there!
23 tháng 8 2018
John's parents gave him a red drum for his eight birthday. When John (0)...opened....his present early that morning, he was very (1).......surprised...........to see a drum inside! He started to play it very loudly. He played it all morning and then after lunch he wanted to play it again. But his mum felt ill. She had a bad (2)...earache...... because John and his drum were so noisy. His dad said, "John, if you want to play your drum, go outside please." John went into the garden and played his drum there. After fives minutes, he (3)........had played........some lovely music. He went out into the street and saw a lot of people there. It was the circus! They drove into town in their lories and trucks. The (4).......driver.........of the first truck stopped when he saw John. John jumped on the back of the truck and (5).......went......... into town with them. He played his drum all the way there!
21 tháng 3 2016
Thời gian Bob chạy 36km đầu tiên là 36 : 54 = 2/3 h
Thời gian Bob chạy 96km còn lại là 96 : 72 = 4/3 h
Tổng thời gian Bob lái xe từ thành phố P tới thành phố Q là 2/3 + 4/3 = 2 h
Tốc độ trung bình của Bob khi lái xe từ thành phố P tới thành phố Q là (36 + 96) : 2 = 66 km/h
We have \(\dfrac{s}{\dfrac{t}{2}}+\dfrac{s}{\dfrac{t}{2}}=40+60=100\)
After that. we have:
\(\dfrac{s}{\dfrac{t}{2}}=\dfrac{s}{\dfrac{t}{2}}=\dfrac{s+s}{\dfrac{t}{2}}=\dfrac{2s}{\dfrac{t}{2}}=\dfrac{4s}{t}\)
\(\Rightarrow\dfrac{s}{t}.4=100\)
\(\Rightarrow\dfrac{s}{t}=\dfrac{100}{4}=25\left(\dfrac{km}{h}\right)\)
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