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Aplikasi Operasi Pecahan, Simak Pembahasannya (Kelas 7 SMP)

August 30, 2020  ,  No comments

Pembahasan Buku Paket Matematika Kemdikbud Hal 76-78 Nomor - nomor tertentu.

  1. Harga suatu barang naik 20%. Jika harga sebelum kenaikan adalah Rp8.000,00 maka harga setelah kenaikan adalah ….

Jawab :

Naik 20 % = 

          {"type":"$","id":"1","code":"$\\frac{20}{100}\\times8.000=1.600$","font":{"color":"#000000","family":"Arial","size":11},"ts":1598846405032,"cs":"1s581XiPjLXvD8tLd7DFdA==","size":{"width":156,"height":21}}

Harga setelah naik 8.000 + 1.600 = 9.600

Jadi, harga barang setelah kenaikan adalah Rp9.600,00

  1. Karena tidak mengerjakan tugas, 9 orang siswa diberi hukuman menulis kata “tugas”. Tiap - tiap siswa harus menulis {"font":{"size":12,"color":"black","family":"Arial"},"id":"2","code":"$\\frac{2}{3}$","type":"$","ts":1598846829368,"cs":"eAG395cNhxOB56OBmwHuJg==","size":{"width":16,"height":24}}halaman buku. Berapa halaman buku, hasil menulis kata “tugas” itu ?

Jawab :

Banyak halaman = 

{"code":"$\\frac{2}{3}\\times9\\,=\\,6$","font":{"family":"Arial","color":"#000000","size":14},"type":"$","id":"3","ts":1598847206507,"cs":"r9WwzaMrlevqPBHsIKuGjA==","size":{"width":105,"height":28}}

Jadi, banyak halaman menulis kata tugas adalah 6.

  1. Seorang penjahit menerima {"font":{"size":12,"color":"black","family":"Arial"},"id":"2","code":"$\\frac{2}{3}$","type":"$","ts":1598846829368,"cs":"eAG395cNhxOB56OBmwHuJg==","size":{"width":16,"height":24}}kain putih berbunga - bunga untuk dijadikan sapu tangan. Untuk tiap sapu tangan memerlukan {"type":"$","id":"4","font":{"color":"black","family":"Arial","size":12},"code":"$\\frac{1}{6}$","ts":1598847486873,"cs":"vplaDeEjLIDC+gPhZ8REZg==","size":{"width":16,"height":24}}m. Berapa banyak sapu tangan yang dapat dibuat?

Jawab :

Banyak sapu tangan =

{"font":{"size":14,"family":"Arial","color":"#000000"},"code":"$\\frac{2}{3}\\,:\\,\\frac{1}{6}=\\frac{2}{3}\\times\\frac{6}{1}=\\frac{12}{3}=4$","id":"6","type":"$","ts":1598847917811,"cs":"1HlUnrt5281a7w0gGpcuPA==","size":{"width":253,"height":28}}

Jadi, banyak sapu tangan yang dapat dibuat ada 4 biji.

  1. Ibu menerima gaji untuk 2 bulan sebesar Rp3.000.000,00. Untuk biaya sekolah anak - anaknya, ia harus menggunakan uang sebesar {"font":{"size":12,"family":"Arial","color":"black"},"code":"$\\frac{4}{5}$","id":"7","type":"$","ts":1598848034774,"cs":"GsRRwk0WrAs6cCbPeIw6+A==","size":{"width":16,"height":24}}dari gaji satu bulan. Untuk kebutuhan belajar dapur, ia harus mengeluarkan uang sebesar {"code":"$1\\frac{1}{2}$","type":"$","font":{"size":12,"color":"black","family":"Arial"},"id":"8","ts":1598848131512,"cs":"gS19QoWLalZSBNWdRm4kww==","size":{"width":25,"height":24}}dari biaya sekolah. Berapa rupiah untuk keperluan dapur ?

Jawab :

Gaji satu bulan Rp1.500.000,00.

Biaya sekolah =

{"id":"9","code":"$\\frac{4}{5}\\times1.500.000=1.200.000$","type":"$","font":{"family":"Arial","size":14,"color":"#000000"},"ts":1598848299555,"cs":"7t3GJsAL3xknD/kW6n4NRw==","size":{"width":258,"height":28}}

Dapur =

{"id":"10","type":"$","font":{"family":"Arial","size":14,"color":"#000000"},"code":"$1\\frac{1}{2}\\times1.200.000=\\frac{3}{2}\\times1.200.000=1.800.000$","ts":1598848411619,"cs":"fQKgYl3GyrqTP4W98mSFNg==","size":{"width":437,"height":26}}

Jadi, biaya dapur sebesar Rp1.800.000,00

  1. Seorang pemain sirkus akan mempertunjukkan berjalan di atas tali yang panjangnya 10 meter. Sekali melangkah, ia mencapai ½ meter. Berapa langkah yang dibutuhkan agar sampai di ujung tali ?

Jawab :

Banyak langkah =

{"id":"11","code":"$10\\,:\\,\\frac{1}{2}=10\\,\\times\\frac{2}{1}=20$","font":{"size":14,"family":"Arial","color":"#000000"},"type":"$","ts":1598848835629,"cs":"Mu9tEBvm67KedEa89df5Fg==","size":{"width":221,"height":26}}

Jadi, ada 20 langkah sampai di ujung tali

  1. Agung melakukan perjalanan mudik dari kota Semarang ke kota Yogyakarta. Di perjalanan pengendara tersebut mengisi bensin tiga kali, yaitu {"type":"$","font":{"color":"#000000","family":"Arial","size":14},"code":"$\\frac{8}{5}$","id":"15","ts":1598849089798,"cs":"mzIfSOPVYQuah111gjjB8g==","size":{"width":17,"height":28}}liter, {"id":"13","type":"$","code":"$\\frac{7}{5}$","font":{"color":"#000000","family":"Arial","size":14},"ts":1598849007313,"cs":"d9ANKM+0tDTqjX3WXffX3Q==","size":{"width":17,"height":28}}liter, dan {"code":"$\\frac{12}{5}$","id":"14","type":"$","font":{"family":"Arial","size":14,"color":"#000000"},"ts":1598849029317,"cs":"bWGMid3yTOzcE1lhTaASsg==","size":{"width":25,"height":28}}liter. Berapa liter bensin yang telah diisi oleh pengendara tersebut selama perjalanan mudik?

Jawab :

{"font":{"family":"Arial","color":"#000000","size":14},"id":"16","code":"$\\frac{8}{5}+\\frac{7}{5}+\\frac{12}{5}=\\frac{27}{5}$","type":"$","ts":1598849209622,"cs":"ntFK2tgsHkJTk9uPixK9tg==","size":{"width":172,"height":28}}

Jadi, liter bensin yang sudah diisi sebanyak

 {"code":"$\\frac{27}{5}=5,4$","id":"17","type":"$","font":{"color":"#000000","family":"Arial","size":14},"ts":1598849270264,"cs":"JrNsssdB7GDhpX7KRFdXIg==","size":{"width":88,"height":28}}

  1. Edi akan memagari kebun bunganya. Untuk itu, ia memerlukan tiang - tiang yang tingginya 1 ½ meter. Berapa banyak tiang yang bisa dibuat dari sebatang besi yang panjangnya 12 meter?

Jawab :

{"code":"$12\\,:\\,1\\frac{1}{2}=12:\\frac{3}{2}=12\\times\\frac{2}{3}=8$","font":{"color":"#000000","family":"Arial","size":14},"type":"$","id":"18","ts":1598849459647,"cs":"EZPD5AfGer0HjQG2dSus2w==","size":{"width":308,"height":28}}

Jadi, ada 8 tiang yang dapat dibuat.

  1. Seorang penggali sumur setiap 2 ½ jam dapat menggali sedalam {"id":"19","type":"$","code":"$2\\frac{2}{3}$","font":{"color":"#000000","size":14,"family":"Arial"},"ts":1598849528563,"cs":"Zgjy/DPj2f7nS2W8LdIHkA==","size":{"width":28,"height":28}}meter. Berapa dalam sumur tergali, jika penggali bekerja ½ jam?

Jawab :

Dalam 2 ½ jam jika menggali tiap ½ jam, maka ada

 2 ½ : ½ = 5/2 : ½ =5/2 x 2/1= 5 penggalian.

Dengan demikian kedalaman baru ditempuh

{"type":"$","font":{"size":14,"color":"#000000","family":"Arial"},"code":"$2\\frac{2}{3}:5=\\frac{8}{3}:\\frac{5}{1}=\\frac{8}{3}\\times\\frac{1}{5}=\\frac{8}{15}$","id":"20","ts":1598849878976,"cs":"gijItVoXS3ol+6UCQuvjpg==","size":{"width":293,"height":28}}

Jadi kedalamannya baru mendapatkan 8/15 meter.

(Oleh Tundung Memolo)

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